[New Player] Some questions about hideout/stash and Level

I'm a new player, and this is my second post. I currently have around 70 hours in the game. First of all, I'd like to thank everyone who replied to my last post. Honestly, it was the first time I've posted in a competitive game's community without someone calling me trash or telling me to quit. So, thank you.

Anyway, I have a few questions, and I'd also like to share some things I haven't really enjoyed.

To be honest, I've been rushing quests a bit, but I've also spent a lot of time farming loot, which allowed me to save up around 6 million roubles. My goal was to reach level 15 so I could finally buy the items I was missing for my Hideout upgrades and get some storage cases.

But once I reached level 15, it was nothing but disappointment.

I spent all that time farming money for basically nothing. Almost every item I wanted is locked behind level 20 or even level 30. Since I plan to Prestige—and the first Prestige is at level 25—it completely killed my motivation. Now it just feels like I'm rushing quests for no real reward.

I know some people will probably say, "Just don't Prestige."

But I'm a new player. Right now I'm still learning, but in the future I'll improve, and I don't want to regret spending 500 hours on the game without getting a single Prestige.

At the moment, my inventory consists of a Lucky Scav Junk Box (which I bought), one medical case, and one weapon case (both given by the game). Other than that, it's mostly ammo, Hideout upgrade materials, and medical supplies. I don't even own a single spare weapon or armor—just a bunch of backpacks filled with loot.

I also tried finding an ammo case on Customs (without opening the locked room), but I couldn't find one.

Honestly, I feel pretty lost right now. I don't really know what I should be doing, and I'm not enjoying the quests that much. A lot of them require running across half the map, which really kills my motivation.

And to be honest, putting all this effort into quests when I'm going to lose almost everything after another 10 levels because of Prestige doesn't really feel worth it.

So if anyone has any advice on what I should focus on, I'd really appreciate it. I've been playing very safely lately. In my last 70 raids, I think I've only run into PMCs about 5 times.

I also have a few questions:

First, are the Seasonal Character rewards cosmetic skins? If so, do they stay permanently on your account, even after a wipe or Prestige?

Second, do you really lose everything when you Prestige?

Third, are achievements permanently tied to your account?

Fourth, should I sell about half of my ammo? It's taking up most of my stash space.

Fifth, should I stop playing so safely, focus more on my quests, and actively look for PvP?

Sixth, I'm starting to feel like upgrading my Hideout isn't worth it if I'm going to Prestige anyway. What do you think?

Finally, I already have around seventy hours in the game. I didn't even rush that many quests, but I hope that next time it won't take me another 70 hours just to reach what now feels like a pretty useless level 15.

Ty for the help

(I forgot to add, but do you guys recommend me as a new player playing seasonal character? Since, my "original" characters will get "delayed" on loot and progress?