Congrats on the Forza. Great coach.
And, all those manuals are available online as well! Plus, you'll find plumbing and wiring diagrams and a terrific interactive, 3D parts catalog for your RV and at Winnebago.com in the Owner's section.
Yes, prolonged sitting can rust the rotors and make the brakes squeak and groan but generally that should wear off pretty quickly when driven.
The 3D parts list will show you the location of the Reservoir. Here's a link to get you started but you'll need to find the right one for your rig.
Seems they are doing some maintenance on the webpage. But here's a link to the Owner-Tools section. Click on 3d Service Parts Lookup.