Personally, I think an insulating surface is better for electronics - there is less of a risk of a short if a wire falls off. That being said, aluminum is stronger than plexiglas and most other insulating surfaces.
As for easily detachable... Yes, it is definitely a good idea to make all wires as accessible as possible. A detachable panel may be a good thing.
Velcro, in my opinion, is a very bad idea. It is not strong enough for what the bot will have to endure during the match. If the velcro falls off, so does your RC/speed controller, then the wires are going to be ripped off, and you'll short the battery. Definitely not a good idea
Motors and fuses going bad... It could happen, but it did not to our team. You can check fuses with an ohmmeter to see if they are ok. As for motors... You can bring spares if you want (it would be the best thing to do), but if you cant get spare motors, FIRST should have a limited supply at the competitions.
The motors should not get hot if your gear ratios are right. If they do get hot, a fan will not solve the problem. There was already a thread about this.
Of course, anything could go wrong at any time
Just do your best to avoid obvious mistakes.