Any rom will describe installation in the first post.
All roms are deodexed and most bloat removed. Some even replace apps using Motorola's Blur so they are more like Google's interface (AOSP). This means that you might not be able to use programs you're accustomed to, like dialer, camera, email. Some roms are already styled, some look like stock. Most roms are optimized for speed with various tweaks.
A Blurry rom like Apex, Rubix Blurry or DarkSlide will be closest to a stock rom w bloat removed.
Roms like GummyJar, Fusion, Liberty, have most or all Blur removed.
The rom version has to match your current version, which for most people by now should be 2.2.340. Installing a rom designed for 2.3.15 will cause problems.
Always make sure you have a recovery backup of your current setup so you can get the next OTA. Also, if you don't like a rom, you'll have a backup to restore. This goes for your first rom, if you like it, back it up so if the next rom doesn't work for you, you can go back to a recent one. Also, you should backup a rom before installing a theme so you can load a stock rom before installing a different theme.
You should also have a program like Titanium backup and backup everything so you can reload call/text logs and contacts, along with app data.