It's random. Just like if you stuffed your hand in a bag of toy TVR's, BMW's, and other cars, there is no certain order.
Not really sure what you mean by this. The cars in the OD are chosen by PD and are the same for everyone, though the paint jobs may differ from person to person.
It changes every 2 weeks, with an FGT, a truck and a Veyron (correct me if I'm wrong) always taking the last 3 slots.
It often has those 3 in, but not always.
Personally I always found it more fun to collect cars via the regular used car dealership, somehow more challenging, but I can totally see why PD put the OD in.
Also I sometimes seem to find more obscure paint jobs in the OD, and some people love to have the cars with 0 miles on the clock, though personally I don't really get that. Cars are to be driven and anything with around 3,000 miles or more just needs an engine overhaul to make it as good as (or better than?) new. But each to their own.
I did find it interesting though when they recently had standard versions of some of the premium cars in there, such as the TVR Tuscan. I thought i'd collected all of the standards but had never seen this, I think there were one or two others too. Interesting, but also kinda pointless
