That's a lot of questions in one paragraph.
Here is a link to the Hi-Lo brochures collection, click on 2000 then 2006. https://www.hilotrailer.com/home/then
The exterior is fiberglass and cracks can be repaired.
The A/C shroud is available from any RV dealer or online. You just have to match to what you have. Most components outside of the lift system and the frame and body are pretty much generic. An online search or Amazon will produce most of what you're looking for. Hi-Lo parts can be procured from JR Repair, Home - JR REPAIR
I recommend that you store the trailer in the down position to relieve strain from the lift system.
Rodents love to chew on things so remove anything that will tempt them. Food, paper, clothing, etc. Bounce dryer sheets and Irish Spring soap chunks placed everywhere work well to repel pests because they don't like strong scents.
I have no recommendations on back up cameras.
Many of us have small inverter generators like Honda or Yamaha. They work well if you just want to charge the battery and run small appliances. If you want to run an A/C or microwave etc. you will need a larger capacity generator.
I hope this has helped.