Well, lots going on here. If the basement is BELOW grade, usually, a vapor barrier is installed. This is because the 'ground' (below grade) is at a relatively constant 55 degrees, and any warm air coming in contact w/that cool wall, will most likely have moisture in it. Thus, condensation. HOWEVER, if there is a 'space' behind the wall, like say about 3-4", then a vapor barrier may not be necessary AS LONG AS air is allowed to pass 'around' the entire room and there are some 'vents' in the wall that allow air to get back there. (Usually, there are vents at a high spot and a low spot that allows air to 'circulate' behind the wall.)
If you need to protect the pipes from freezing, buy the flexible pipe insulation-tubes from Home Depot or ***** or some place. As for where to put the pipes, let the contractor do what he wants to do. I'll bet he wants to put the piping in the 'middle' and the electrical behind the insulation. NO matter - you can 'slit' the insulation as needed.
You should be worried about someone hanging pictures and such. If the wires or the piping is UP AGAINST the backside of the drywall, guess what might happen??? What you might want to do is take pictures BEFORE the insulation is installed so you know where 'everything' is. Also, consider running Cable TV cables to CTV outlets on EACH wall even if you don't use it. You never know when you, or a future buyer, may rearrange the room. The same goes for phone lines. Be aware - You can't 'mix' certain types of wiring. There's a thing called 'interference' so find out what wires should be run separately from each other (electrical included), and how far 'apart' from each other they should be run.
My best to ya and hope this helps.
Jay J -Moderator
PS: God Bless America!