Even though we have a Friendship, I can't tell you anything specific about this model that would not apply to all models.
You didn't state if you were an experienced RVer, so forgive me if you already know all of this.
1) Look for stains on the walls, ceilings, floors, inside basement compartments and overhead compartments, and under rugs and in corners. These may be signs of water leaks.
2) Make sure all the plumbing systems work. Hook up to a water line and run all faucets and flush toilet. Look for leaks around toilet, at faucets, under sinks and in compartments below. Make sure the waste valves are not leaking.
3) Fill the fresh water tank then turn on the fresh water pump and repeat the above plumbing checks.
4) Make sure the water heater works on both gas and electric if so equipped.
5) Run the slides in and out and watch for smooth action and tight seals when in and out.
6) Turn on the furnace(s) and A/C system(s). Make sure you get heat and the heat stays on. Same with A/C
7) Run the generator and be sure it is producing the electricity you need to run A/C, microwave, AV systems, etc.
If you are not automotively inclined, find yourself a diesel mechanic, pay him/her to go with you, and let him/her inspect the things a mechanic would know about.
9) Learn about date codes on tires and if they look good, make sure they are not excessively old.
10) Turn on all the electronics (TVs, DVD/VCR, AM/FM, CD/Tape). Have them hooked up to antenna and, if possible, a cable or satelite system.
11) Climb up on the roof and look for damage/cracks. Especially around seals and joints.
12) Test drive it...and drive it like you stole it. See how it performs on hills, under braking, in turns and how it rides.
13) Search this forum for specific topics and you may find more useful info.
Hang in there. I'm sure that many, more knowledgeable than I, will respond with additional information and answers to your other questions.
Best of luck!