ING is VERY easy to have multiple accounts.. and you see them all together on one summary page. You can nick name them as well (kinda like an "envelope" system). I think they are one of the easiest banks to open multiple accounts with - just click "open new account" and verify you are logged in.. say its just you (and not a joint account) and bam, your new account will show up immediately on your main summary page. The trade off is that ING doesnt have AS high a rate as other online banks... but this doesnt particularly matter until you start getting into the very HIGH amounts of money.
The amount of interest lost is minimal if what u are shooting for is convenience.
How many months is the 0%? More importantly, at what point does your cc debt start accruing interest (look out for terms like "the first billing cycle that includes such and such a date". Take the number of months and divide them into your total cc debt MINUS your estimated future minimum payments until then. Then put that amount into your interest bearing savings account and do not touch until its time to pay off the entire balance (which should be right before the roll over date where it converts to interest accruing debt).
For instance, if its 12 months @ 0%... $3600 - (minimum payment..maybe $60/month..$720) = $2880 to save for. 2880 / 12 months = $240 a month to put into a savings account for debt (or just $60 a week). Then, when its time to pay off the entire credit card, you will have the exact amount plus any interest that has accrued.