Tax Implications

I've been DCA'ing monthly into Ethereum, Doge and Shiba since late 2020. I'm working on my strategies for cashing out of this bull run and then buying once things level off again. But I have a few questions and concerns, especially since this run has yielded some real money that I know Uncle Sam wants a piece of.

1. My first question is on cost basis and my DCA. I'm assuming that right now, any money I invested more than 1 year ago is Long Term Capital Gains, but if I sell part of my bag, which equity goes first (the most recent equity or the oldest investment money)?
2. If I sell today and buy later this week (say if there is a sudden correction down 30-40%), I assume I reset my cost basis to whenever I buy again. But if I keep buying dips and selling climbs, am I getting hit every time for short term gains after that? I just want to clarify for sure that day trading has taxable implications every time even if it is the same product (I remember a long time ago reading that buying and selling the same mutual fund in the same day may not have implications, but I could have misremembered).

Thanks for any tax clarification you can offer, and I hope you are enjoying the ride as much as I man.