Moodle.org is always a wealth of knowledge from all sorts of angles and contributors. Here’s a great Doc page which features a lot of what you need to know when evaluating Moodle (especially if you’re evaluating whether or not to host it yourself): http://docs.moodle.org/en/Installing_Moodle#Hardware.
Installing Moodle through a cPanel (like what I use at Bluehost) is very easy and convenient, however for usage at a school when more than 5 people might be accessing a resource/activity at the same time it’s highly recommended that you host with a partner, another 3rd party or self-host to ensure that you’re providing enough RAM and hard drive space to allow your Moodle to run effectively. This Doc gives a rough estimate of what hardware you’ll need to support your students and organization effectively.
An estimation guideline states that you should be prepared to have 1 GB of RAM on your Moodle server for every 50 concurrent users. Or 20 MB of RAM per student at a minimum (the more to spare the better). Check out all of the recommended hardware/software needs at http://docs.moodle.org/en/Installing_Moodle#Hardware.