JJ, personally, I would upgrade to 4.9.1 and stay there for a bit longer. There are a few issues with 5.0.0 that would prevent me from using it in a production environment.
There are a number of blog posts out there discussing how to upgrade. Personally I would do this.
1. Backup everything, website and database
2. Download the 4.9.1 upgrade package from dotnetnuke.com
3. Extract the upgrade package to a folder on the computer
4. Copy the contents of the upgrade package directly over your current DNN site
5. Hit the site and make sure it upgrades.
It should be that simple, you do not have to reinstall modules when you upgrade a DNN site unless something went terribly wrong.