Credit Card Transactions

Hello, this site usually seems a bit empty so I thought i'd try and fill it a bit with a genuine enquiry - hopefully some kind soul will have time to help me. I'm just writing my start-up business plan and am looking for definitive information about how credit card transactions will work, what I need and how much it's going to cost. I'm getting bogged down looking at individual sites on the internet that are geared towards selling a particular product. I will have a website which will need to take transacions and I will need a mobile credit card terminal as I will be out and about selling. 1. Lots of companies seem willing to rent/lease equipment but is buying an option and from whom and what sort of price? 2. Will the website payment system need to be different from that needed for the moibile unit or can they be some how combined? 3. How does a merchant account work - do I automatically feed card tranactions into this and then from this into my business bank account? 4. At what stages do I encounter fees for having this facility? As you can tell by my questions I'm clueless at the moment but hope someone can help. Thank you Andrea