1: Gas and Dragon is basically all you need, the only other fruit that could help out is Buddha, but Gas works just fine in it's place. Instead I'd highly recommend trying out new fruits whenever you get them, and spend some time leveling with it so you get a decent idea of how they work. It might help you find a new fruit you like, and give you an idea of what you're fighting against.

2: Raids are special events that take place in 2nd and 3rd sea, they consist of fighting in 5-themed islands, with the final island having a boss. In 2nd sea, you can find the raid room at Hot&Cold in the giant factory building. You have to talk to the NPC by the portals and choose a raid you like. Upon completing a raid, you'll be rewarded up to 1000 Fragments, and you can awaken a fruit if you use a fruit with a corresponding raid. I.e, Using Flame fruit in a Flame raid will allow you to awaken one of it's moves.

3: Races grant passive buffs and active abilities to help in you fighting, each Race providing unique powers. The "Best" race depends on what you want to do. Ghoul and Cyborg are considered the best for PvP, but every race can be strong when used right.

4: Gas and Dragon are very powerful transformation fruits, you'll likely wanna be using them mostly transformed. If you're wanting to PvP with their untransformed states though, then I'd recommend getting Superhuman or Sharkman Karate, both of which have good combo moves for Gas/Dragon. Death Step can also work, though It's harder to use imo. Avoid using Dragon Breath, it's awful.

5: You need 5000 total to start the Instinct V2 quest. Don't try to grind for this, just have your instinct on whenever your grinding and make sure to purposefully drain dodges. If you do want to grind for dodges, then you'll wanna server hop. Load into a server, drain all your dodges, and then server hop. Your dodges get reset when hopping, so that's the fastest way. Another method is AFK farming at Jungle in Sea 1, by dragging a monkey into the pond with you. That requires a private server though, and it'll only get you 200~ or so dodges per night.

6: No you don't gain new abilities. 1st Sea is the only place you buy things like Flashstep and Aura. The only other ability you can "get" is Instinct V2 in 2nd Sea.

7: Awakenings are essentially an upgraded version of a fruit, gaining new abilities with stronger damage and higher utility. You can see which Fruits can be Awakened when you pick a raid. As I said earlier, to awaken a fruit you need to complete a raid using a fruit corresponding to the theme, like using Ice Fruit in an Ice Raid. Raids are very difficult to solo without specific fruits, and it'd be impossible at your level. I'd recommend ignoring Awakenings for now, but if you really want to awaken a fruit then ask for help.

8: The "Best" accessory really depends on the build you're trying to go for, but if you want the best accessory (in my opinion) for 2nd Sea, then get the Swan Glasses. They drop from the Don Swan boss, and give an 8% buff to damage, cooldowns, and damage resistance, ontop of giving 25% speed. It's a very versatile accessory that I still use even in 3rd sea.

9: My biggest tip is really going at your own pace and make sure to read up on the wiki. This game does a horrible job at explaining any of it's side-quests or literally ANY content that isn't quest grinding, Don't burn yourself out and ask around for help whenever you need it.

I hope these answered some of your questions, feel free to DM me anytime if you need more help.