IUSB
iShares Trust iShares Core Universal USD Bond ETF
stock NASDAQ ETF

Correct. Treat your CC holdings as income and nothing more.
To your cash flow concern, turn off DRIP from your income funds and take the capital you get when it hits your account and put it towards one of the index funds. That way you don't actually need to sell anything to take a new position. You are rebalancing in a way. I'm doing this in my Rollover IRA. It was geared toward income only but have been shifting it towards my personal 3 headed monster of ITOT/IXUS/IUSB.
I can't answer your last point. Only you yourself know how aggressive you can or want to be. It all depends on your risk tolerance. In my Roth and HSA, I'm 90/10 stocks to bonds which is hyper aggressive. Moderate aggressive begins 60/40 or 70/30

All the retiree funds like VTINX , AOK etc have a huge chunk of intermediate bonds and these old school retirement experts all say the majority of your fixed income should be in intermediate bonds like BND, IUSB watch rob berger on YouTube.