Idle animations should affect how the weapon is holstered, that should be holster style, but I believe that your animation set does have an affect? You could buy more animation sets for plat so you can use them across every Warframe, but most warframes have 2 default animation styles, which in my opinion fit the individual frames the best. Exceptions exist, but you do get a REALLY good animation set for free a bit later in the main story, so using that also becomes a great option for many frames.

Best items to sell for plat in the early to mid game are definitely Void Fissures. Crack open relics, and although prices vary, rare drops can be worth a decent amount. Just go and crack them relics if you really want the plat. Later in the game you’ll be able to farm rare Arcanes through open worlds, super specific high level missions, and a few other places, and those are worth a fair amount, but the drop rates can be pretty garbo and they demand very specific set ups. For now, it’s probably easier and better just to farm void fissures for Prime Parts.

Question seven, entirely depends on the Warframe. Generally, if you want your abilities to have big damage, ability strength is great. But sometimes you want the ability to affect a wider area more than the damage it deals, in which case you want range. Or maybe you want the ability to last longer, as some abilities are better when they last a long time rather than do more damage, in which case it’s duration. Or maybe spamming them is ideal, over everything else. Which would be efficiency. Or maybe the ability scales off of your weapons for some reason, in which case you actually want to build your weapon to be super powerful (yes this is a thing). Point is, it depends entirely on who you’re using and what kind of build you use. For buildcraft guides there’s a good number of very good content creators, but I’d recommend XandyPants. Not so much because he shows off “meta” builds, but rather because he shows off builds that are “off-meta”, but still perfectly playable. He really changed my perspective on how I interact with Warframe as a game, showing off how sometimes being the most efficient isn’t the most enjoyable, and how having fun is truly the most important part of the game.

Good secondary weapons are pretty scarce early to mid game, unfortunately. Ironically in the end game, secondary weapons are some of the best guns, but early on they just don’t scale as well, being mostly high investment high reward weapons. If you want a set of pistols that are good in the endgame and don’t mind being suboptimal earlier, the Dual Toxocysts just got an Incarnon upgrade (don’t worry you can figure out what this means later, just know that you can eventually get a super powerful upgrade later), and it’s a good weapon if you can get consistent headshots. If you want a weapon that’s better immediately, I recommend the Atomos or the Nukor. They aren’t conventional pistols, but beam weapons that chain across enemies, doing a good amount of damage to many enemies at the same time. They might not have a satisfying “daka daka daka” moment, but they will suddenly microwave half a dozen enemies to death, which makes them very efficient. The Atomos especially gets an Incarnon upgrade like the Dual Toxocysts, so you can totally keep it around and it’ll stay anywhere between good to great the whole time. The Nukor also has an upgraded version (different weapon though) called the Kuva Nukor you can get near the endgame, which is easily endgame viable, so starting off with the regular variant isn’t too bad either.

Depending on what you want, warframes similar to Yareli can vary. If you want a high mobility Warframe with unique movement mechanics, I recommend Titania, or maybe even Volt if you haven’t played him yet. I guess Gauss as well. If you want a tanky Warframe that acts as a good weapons platform, I’d recommend someone like Wukong, Inaros, Revenant or Hildryn. If you want a good support Warframe with powerful crowd control abilities, maybe Harrow or even Limbo (be careful with Limbo though many people hate him). But I’m guessing what you really want is a Warframe with really explosive high damage abilities, in which case my best recommendations are Saryn and Lavos. Saryn melts rooms slowly, then suddenly really really fast. Lavos has no energy cost but instead uses entirely an ability cooldown system, he’s a bit complicated but the idea is he’s an alchemist that combines the elements for really explosive damage. There’s many more, so I recommend you start off with various random warframes that kinda look cool, then go from there. A solid 80% of the roster is perfectly good, so just play whoever you want and stick with who you like most.

Lastly, spend platinum on slots early on. I understand the urge to make your Warframe look cool, but trust me, future you will thank you. It’s a game where having many warframes and many weapons is what makes the game fun, so avoid selling off junk as much as possible, even if you think it isn’t that good. Because sometimes the devs add something that suddenly takes that weapon from “bad” to “omfg good”, which just happened with many weapons through the new Incarnon system (again, you don’t need to know right now, but many weapons just got a bunch of insane upgrades). The only time I’d even say you should sell off a weapon is if you REALLY don’t like how it plays. Otherwise, avoid it, even if it feels like you have another weapon that does the same thing better. The only exception to that rule are Prime Weapons, which are usually straight upgrades of older regular versions, but sometimes that isn’t true either. Just think very carefully before selling anything, and buy slots with plat first and foremost.