You are charged a listing fee based on the amount you set as the lowest bid. An auction that starts at 99 cents will be charged a lower listing fee than one that starts at $9.99. You are also charged a reserve fee. Apparently the reserve fee is less than the listing fee for starting an auction at a higher bid, because the main reason people use it is to start with a lower bid but not be committed to selling at that bid. I strongly recommend you do not use it, and instead start the bidding at the lowest amount you are willing to accept for your item. Many buyers avoid auctions with reserves.
Ebay will not deduct any fees from your account. They'll send you a statement. You can pay with a credit card or a Paypal balance (there may be other ways to pay, but I don't remember, because I've never used them).
Yes, you can use the same Paypal account for buying and selling. Keep in mind that according to eBay's terms of service, if you use Paypal, you must accept all forms of Paypal, and that means credit cards. If you have not upgraded to a "premiere" account, technically, you must do that before accepting Paypal on eBay. Many buyers are ignoring this rule, but if you refuse to accept a CC payment, you can (and probably will) be turned in and get a spanking.