Rich's advice is best, but heres some "Cliffs Notes" to get you started.
Shipping is listed in the ad for each item.
The 18% buyers fee only applies to auction items." Buy- it- now" items are not charged this fee.
To figure out the fee of an auction item, simply pull up a calculator on your electronic device and multiply your highest bid x .18.
i.e. if your bid is $200. $200 x.18 = $36. Your purchase price will be $236, plus shipping and tax as required.