You can provide liquidity with your sol + usdc and get a nice apr. 25-30%+. Raydium, orca, etc

I can’t say it’s 100% safe, the defi protocol will be the point of failure. But it’s super unlikely. There is also IL.

You can stake your SOL natively with any wallet that can connect to a validator. I use ledger. But solflare is another.

Gm. Are you also growing your sol? Get some sol, stake with validator.com, and off you go. For USDC there is always risk. I like the returns in jup.ag in the JLP peeps program. Also in drift.trade in their insurance program. Returns are much higher but have risks.

I wouldnt even bother for 3% in margainfi or whatever. Risk, which is low, isn’t worth the reward imo

This is an excellent question. However a lot of places you can earn interest on usdc without even having to stake it. Try coinbasewallet. I don’t necessarily use USDC but, I did see they offer (I think) like 5.22% for just holding it doesn’t say anything about having to stake it like with eth, sol, dot, or matic. I personally don’t ever hold USDC at all let alone enough to earn anything though so I could be mistaken. Hope this helps. Wish I could offer more