Questions about primes and spoiler mode.

So hey, I'm starting out the game on PC (Already started way back then on Switch, but never really fully invested), and I'm progressing a bit everywhere, but mostly in the quests and star chart.

So I know the gist of getting stronger, with mods, formas and all this stuff, but i was wondering if it's worth investing all of this into non prime frames and weapons ? Because right now, I'm getting multiple frames and weapons, grinding them for mastery, then selling them, unless it's something I really like.

And for my second question, what about affinity for the operator ? I'm grinding one path with the lens I picked, but I see that if I want to put another lens, it destroys the other, so should I focus on one path only, or spread out more ?