Just a guess: Chase is probably trying to avoid the situation where your MFs are worth $X, you put in an order to sell $X, and at market close (when all MF transactions occur), the MFs have declined in value and are no longer worth $X but are worth 99% of $X.
See if you can find an option to sell in terms of number of shares instead of in terms of dollars. This exists at Vanguard; I don't know if it exists at Chase.
Yes, if selling inside either a traditional or a Roth IRA, there is no taxable event.
Withdrawals from traditional IRAs generally create ordinary taxable income. Withdrawals from Roth IRAs are generally not taxable. If you withdraw from an IRA, generally you'll receive a 1099-R the following January.
No tips. Personally the 3% kicker for Robinhood isn't worth it to me, but I can see the appeal.