Hal,
In regard to your excellent questions
,
1. Yes, you have to remove the bikes before opening. This is not a problem for me, because my children usually want to ride their bikes right away to explore the campground. The Thule bike carrier tips down, so the carrier doesn't have to be removed.
2. The storage compartment is accessible with the bike carrier and bikes installed. The last trip with bikes, I had to use the dump station and I store my sewer hose in this compartment. I was able to get the sewer hose with three bikes on the rack. You just have to access the storage compartment from the sides.
3. The bolt you see in the first picture came with the receiver adapter. You tighten it to stabilize the bike rack. I'm not sure if I really need to use it, but it does seem to make the bike rack more stable. There is an additional bolt that comes with the bike rack that goes through the receiver and threads into the bike rack. You are correct someone could unbolt the rack and steal the bikes. I usually lock all the bikes together and the lock them to the bike rack. Which means if someone was to steal the bikes, they would have to carry or drag off multiple bikes and a bike rack.
Thule does sell a lock (Snug Tite Lock) which locks the bike rack to the receiver.
Specifics on the bike rack can found at:
http://www.thuleracks.com/thule/images/manuals/984.pdf