Nope - HostGator is merely the host (meaning they run your server, make sure it stays up all the time, provides backups on a regular schedule, and helps with all of the technical issues you have with the server, database software like MySQL and PHP) but they're not Moodle experts (though I've found that some of the tech support people knew a surprising amount of information about Moodle. The advertising and promotion of your web site (you do get a full-fledged web site along with the ability to ad Moodle) is all your own.
I'm not sure if they use Paypal - I've always used a major credit card with them. You can probably work something out with the Billing department if you don't have a credit card and they don't have Paypal service, but I wouldn't be surprised if they didn't give that option.
As far as charging for your courses... I have no earthly idea about how you'd go about setting a retail price. I'd probably think of how much it cost me to create the course, how much time I'd spend supporting a student on average, and guess at how many student's I'd have in a six moth period to guess how much it was going to cost me to do the course (obviously setting my time worth some amount of money). That'd at least give me an idea of what the fixed costs were, then go from there. (Can you tell I've done a couple of entreprenuership courses? ).
Oh, forgot to mention that with HG, if you sign up for a longer time, the price per month goes down. And if you just want to dab your toes in for a couple of months, you'll pay a bit more per month, then if you extend the contract, your monthly price will go down.
I'm probably going to be settng up another account this week for myself and some of my compatriots at school who want to get a bit of experience playing with the latest Moodle versions - I've got 2.2.2-1 on my laptop, using one of Bitnami's stack loaders (puts the whole thing, SQL database, apache server, and the latest version of Moodle onto an .exe package that you and use on your laptop - it WILL connect to the internet and can be used as a Moodle server, but being run on a laptop, would be slower than the dickens and not suitable for more than 1 or 2 people online simultaneously. But it's good to play in your own sandbox - my buds, though, have no interest in becoming Moodle administrators, so I'll play that role on my HG account, and let them play the teacher and studen roles. And since there won't be more than 10 or so teachers, with 2 or 3 courses each, the HG baby hatchling hosting server will be sized just right.
Be sure and look at the HG user forums to get an idea of what you'll need to do to install the latest version of Moodle - you'll have to use the latest version of PHP, which isn't a problem, but is not the PHP that's used by default on your hosting server.