As others have said, you can make multiple payments per month. However, I highly suggest you make these payments online as that snail-mail is rather slow, insecure, and can cost you a few bucks per month in postage.
First of all, be very careful with credit cards. You need to make sure you have strong enough discipline to treat it like cash and keep it in alignment with your bank account. There is also a phycological element you have to fight with plastic, which is simply the ease of "swiping it." Many people will simply spend more when they can swipe as opposed to handing out cash.
If and only if you have this discipline, then use it on a regular basis. I would recommend you pick one day a week (Sunday or whatever) where you pay off your weekly balance. That way, you limit your potential to overspend if you only pay it off monthly.
To close, let me again say this: over the course of the first month or two, watch your spending very carefully. If you start breaking your budgets or using more than you normally do. Stop immediately! You can very easily negate or exceed any "bonus dollars" you get. Honestly, that's why they have such programs in the first place, because that 1% to 3% they "give you" will more than be made up (by most people) in the extra spending.
If you can "play the system," then go for it. If not, then cut it up immediately or lock it away in your safe to only use for certain purchases.
Good luck!
