Originally posted by: dullard
1) Yes, they are worth it. For example, I got my Chase Freedom card about 1.5 years ago and I have already received $500 in cold hard cash from them. Absolutely free. I didn't spend much either to get that, nothing that I wouldn't have already spent. If ~$250/year for doing nothing sounds good to you, then you should consider a reward card.
2) As noted above, credit cards with rewards come with high interest rates. Thus, NEVER ever use this for anything that you don't intend to purchase anyways and that you have cash to pay off when you get the bill. If you really must keep a balance, have another credit card with a low interest rate for your balances (but really, you should avoid that as well).
3) Yes, you can pay it through your bank online. Or, just like almost any other bill you can pay it through the other company's website. This latter option is a little bit more work (you have to actually sign in at least once in your lifetime to a website), but you never have to worry about your bank changing their fee structure for their website like banks love to do. Heck, I refuse to use my bank's bill pay to make certain that I never have any bank fees. It is just as convenient to pay from the other end.
4) For most people, the best reward card out there is Chase Freedom.
Click me! You earn 3% cash back on your biggest categories each month and 1% back in all other categories. On top of that, if you let the reward accumulate to $200 they give you a bonus $50 (effectively making it a 3.75%/1.25% cash back card). Also, right now they give you $50 for your first purchase. So, if you get the card now then spend $5000 over the next few months/years, you'll get $250 in cash back ($50 signup + $5000*3% + $50 bonus = $250).
5) Yes, if you are a big spender, there are better reward cards. But those don't work well for most people.