Noob questions

I am pretty new to bitcoin investing. I started about a year ago on Robinhood (since then I’ve been reading it’s not a great option). I recently bought a Trezor but am waiting for it to be delivered (should be here Monday). My plan is to HODL which is why I bought it. I was going to try and transfer to a hot wallet (any recommendations for best one would be appreciated) but at this point feel like it’s kind of pointless with the Trezor coming on Monday.

I have a few questions:

1. Am I able to transfer btc directly to my Trezor or do I need to use another service like a hot wallet?

2. Are there fees to make a transfer to a cold wallet?

3. I am planning on setting up the cash app direct deposit to DCA to avoid fees. I understand it’s recommended to transfer to cold wallet once you have a good amount of sats. Can you transfer directly from cash app to Trezor? What would be the recommendation of the amount of sats to save in cash app before putting on cold wallet?

4. Since most people aren’t a fan of buying on Robinhood (high fees I think?), would Kraken be a better option when buying larger amounts? Or just stick to cash app? Specifically I’m talking about when I have an extra lump sum of money to invest. My understanding of the way you avoid fees buying on cash app is having a direct deposit set up and getting paid partially in btc.

5. Sort of a tax related question if anyone has any idea… I had bought a good amount about a year ago and planned to sell at $60k. I ended up selling at $55k because I got scared then regretted the choice and bought everything back. This was really stupid because I ended up losing money with the Robinhood fees and now I’m wondering if I will have to pay taxes on my gains (even though I reinvested right back into btc the next day). Anyone had something similar happen or know if paying taxes on that money is a thing?

Thanks for taking the time to read. I’ve been really enjoying learning about bitcoin and am excited to be apart of the community here. I appreciate everyone’s insight!