1) I don't know that you need to research it like mad, but you might want to look into it enough that you can do it. The especially cool thing about loss harvesting is that you used up to $3000 as a deduction against ordinary income.
2) Since neither of your purchases were made within 30 days and VTSAX hasn't paid a dividend within 30 days then this sounds right. Since VTSAX will likely pay a dividend next week you need to turn off dividend reinvestment in any account that will continue to hold VTSAX.
3) I'm not familiar with crypto myself, but
https://thedailycpa.com/2017/06/01/the-taxation-of-cryptocurrency/ indicates it's treated the same as other investments, so yes, you could realize that loss in the same way. Note that you can only claim $3000 of losses that aren't offset by gains against ordinary income, so you won't get that full deduction this year, but the loss will carry over to next year when it can offset any income to the extent that the carry over loss exceeds next years realized gains.
4) Yes, reinvested dividends are just a service provided by your brokerage to automatically buy the investment using the dividend, so any such purchases currently showing a loss could also be sold to realize that loss. The flip side is that reinvested dividends resulting in the purchase of an asset with 30 days of a sale at a loss of that asset will cause a wash sale, so if you're going to tax loss harvest you need to turn off dividend reinvestment in all accounts that hold that investment.
5) Yes, any investment that is currently showing a loss can be sold to realize that loss. If you've held the investment for more than a year it will be a long term loss which can offset long term gains and the excess can offset ordinary income. Investments sold at a loss that were held less than a year will result in a short term loss which can offset either long term or short term gains, or ordinary income to the extent that the loss is greater than the gain.
I've alluded to it above, but make sure you don't rebuy an investment that you sell at a loss within 30 days before or after in ANY account. Some people say this only applies to IRAs in addition to taxable accounts because the IRS has specifically mentioned IRAs in relation to wash sales, and hasn't specifically mentioned 401(k)s/etc, but I wouldn't risk it -- I'd just assume you need to follow the rules for all account types.
Since you mention not buying "similar" investments, note that the actual standard is "substantially identical." This is obviously a term that is up for interpretation and the less alike two investments are the safer you are. Some people might even argue that you could rebuy VTI since it's an ETF while VTSAX is a mutual fund, but I wouldn't feel comfortable doing this. I am, however, comfortable buying a mutual fund or ETF that is still a US total market fund as long as it follows a different index than the one I sold. VTIAX would certainly work as it follows international, but you could get closer if you want too.
One final thing to note if you plan to sell some but not all of an investment in an account is that you want to tell your brokerage that you want to use specific identification cost basis tracking which means you can choose to sell particular groups of the investment based on when you buy it. If you don't do this they may use some other method like average cost (just take the average cost basis of all shares and use that as the purchase price), or first in first out (FIFO - sell the first thing you bought), both of which could cause a wash sale even if you sell the same number of shares as you bought within 30 days.