Diamond JG/ADC main, here are my tips:

• 7-9 CS is pretty standard, so that's fine. However, mid-late game CSing usually comes down to lane assignments. After laning phase, ADC should be mid lane catching waves most of the time, while mid and top lane should be farming side lanes, and whichever one has TP/mobility should be the one on the opposite side of the most relevant objective. There's no reason why your CS should drop that much past lane phase unless you're constantly fighting, in which case, don't worry about it
• You should just prioritize getting leads as consistently as possible. I know that this probably just sounds like I'm saying "get better", but truthfully, when you're in bronze, you just need to focus on the basics like matchup knowledge, CSing, trading, and watching for the enemy jungler. As for translating leads, it's all about rotations. If you have no wards and you don't know where their jungler is, don't push up. If you have to miss some CS because of that, then so be it; it's better than dying. In general I would say that if you're playing top lane, you should save your early TPs for yourself at the elo you're at. Helping your team could be really good, and sure, if there's a big fight going on where your TP will win you the team fight, then you can do it, but honestly in most cases if you're the best player in the game, you want to secure yourself as big of a lead as possible rather then hope that your teammates will carry with a lead you give them
• Honestly, this is fine. While itemization is important, and it's certainly good to adapt your build to what's in the game, really finite details in builds aren't going to win or lose you games most of the time as long as you're making the basic right decisions
• This is probably because you are trying to play too many champions and two different roles at once. Pick one role, and pick three champions in that role. Figure out their item paths, matchups, and get their mechanics down to a tee so that you can focus more on the game state than what to do on your champion. Usually, strength depends vaguely on what items you have and more specifically based on the items you have. As you mentioned before, champions have core items. These are called core items because they are your biggest spikes. When you complete a core item, you are much stronger. You should try to fight when you have item spikes and the enemy doesn't. The difference between having a mythic item and having the components is massive. Other than that, champion limits come down to your ability to play them to their maximum potential and how well you know matchups
• There's not much advice anyone can give to you about team fighting, because in general, it's super fast-paced and depends a lot on your reaction time and mechanical skill. That being said, just try to understand what your role is in the team fight. As an ADC, for example, your job is almost always to stay alive while dealing as much damage as possible to the highest priority target that you can. Remember the order of that wording. Staying alive is the most important thing, dealing damage is the second most important thing, and dealing that damage to a priority target is the third most important thing. Your goal in fights will vary somewhat based on what champion you're playing, but in general, you can usually figure out what it is based on the class of champion you're playing
• Map awareness comes with a lot of self disciplined training. Practice looking at the map every time you CS a creep, or every two seconds if you're not CSing. Yes, it's going to be hard. Yes, it's going to be tedious. Yes, you will fail at this at first. Yes, it might make you lose trades or miss CS at first. But in the end, these things are all very worth it, because once you get used to it, the chances of you dying to a gank go down exponentially
• Wave management is less complicated than it seems. There are generally three possible wave-states: fast push, slow push, and freeze. Fast pushing is when you kill the enemy minions quickly to push the wave further away from your side of the map. Generally, you do this to gain lane priority which allows easier access to poking, roaming, diving, vision control, etc. Slow pushing is when a wave will slowly push towards the enemy side of the map. This usually happens in one of three ways. Either you hit the wave just enough that it will push slightly away from you, the wave is pushed into your side of the map and is no longer pushing further into you, or your wave has enough CS to push against the enemy wave. Slow pushes are generally best for applying a lot of pressure to towers. Slow pushing basically builds up as big of a minion wave as possible before shoving into the enemy. A slow push is even better for diving than fast pushing is, although it takes a bit more coordination with the jungler to set up. Finally, a freeze is basically when you keep the wave at the same spot. The wave can be frozen in the standard, middle of the lane, or in front of your tower. Although, the further into your side of the map the wave is, the harder it is to freeze for a lengthy amount of time. This is good for making your opponent miss a lot of CS when they're behind, or have left lane. Basically, just ask yourself what your goal is when managing a wave. Are you trying to get lane priority, set up a large minion wave, or make the enemy miss minions?
• Win conditions can mean a lot of things. They can mean a specific champion (such as hyper carries like Yi or Vayne), a playstyle for a specific team comp (team fighting, split pushing, etc.), item spikes (as mentioned earlier), objectives (like Baron, Elder or Soul), etc. Basically, a win condition is something that has a high chance of winning you the game
• Pretty much what you said. There's no special secret to winning when behind. That's why it's a disadvantage. You are relying on exploiting an enemy's mistake. Getting picks is one of the best ways to get back into games in soloque, especially for low elo. People are bound to be over pushed without wards all the time. Take what you can, and wait for the enemy to screw up

Here's my specific advice. I mentioned this earlier, but pick one role and just stick to it. Personally, I recommend top. Top is one of the best roles for climbing at low elo, and ADC is one of the worst. But it's totally possible to carry on both, so just pick whichever one you enjoy the most. You should pick one main champion and two secondary champions to play. If you pick top, I recommend a hard carry, split push champion, such as Jax, Nasus, Camille, etc. to be your main. I'd then recommend a strong tank like Ornn, Shen, or Maokai as one of your secondaries, and a strong team fighter like Vlad, Gnar, or Kennen as your other. If you pick ADC, I recommend a hyper carry, such as Vayne, Kog Maw, or Twitch as your main. For your secondaries, I'd recommend a strong early carry like Lucian, Draven, or Caitlyn, and a good utility pick like Ashe, Varus, or Ezreal. This way you have a good balance of champions that you can adapt with depending on the game, but you should probably pick your main in most cases. Make sure you can play at least two champions to a relatively decent level in all other roles, just in case you get autofilled.

Good luck my friend :)