With regards to saddles, the Brooks B17 is an excellent saddle. Be warned, however, that they can take 1000 miles or so to break in. They don't suit everyone so my advice would be to go with the standard saddle and see how you get on with that first. Brooks also do a pre-aged saddle which makes the breaking in process a little easier.
With regard to lights, it may be worthwhile to consider a front wheel dynamo, Shimano produce a very good product. You can then have your lights on permanently without having to worry about batteries. Failing that, Topeak (I think) make a very nice solar powered light.
Plenty of choice on bar bags bu probably Ortlieb is your best bet and most easily available. My own choice would be Carradice but I don't think they're easily available in the States.