You will have to stop at the front desk to turn off room charging for those you don't want to have it. Or just don't tell them what the PIN you set is. All touch to pay purchases require a PIN.
I did online check-in for VGF, it allowed me to skip the credit card. I was using gift cards. You could then add it when you get there and designate which bands.
Redeeming a "handful of cards" takes time, for both you and the CM. There is another way to do it that doesn't waste your valuable vacation time, and can get you a monetary award. Sign up for a Disney Vacation Account. Then, at your leisure, enter your gift cards into your DVA. The later transfer from your VGA to your room charges will then be quick and easy. Another DVA benefit is that you get a $20 gift card for each $1000 of DVA spending.