If you've got an 85 with the original hotair ECM, then unfortunately theres no real choices for scantools. At least, this was what i remember from when i looked into this years back (maybe i am remembering wrong, or things have changed since then). Or maybe the scanmaster will work, but it doesn't show nearly as much information as on the newer ECM's? Either way, its not worth it to drop a few hundo on a scanmaster for the stock ECM.
Good news is though, that its relatively easy and straightforward to convert to the 86/87 ECM, and not too much money either. The advantages of doing this, in addition to being able to run a scantool of some type is that the engine will run better, there is a lot more availability of chips, and replacement ECMs are a lot easier/cheaper to find. If you do convert, I would definitely reccomend a TurboTweak chip. Let him know its for a hotair with the 86/87 ECM and he will hook you up with a great chip.
The conversion pretty much consists of getting a good working 86/87 ECM from someone here on the board, getting the chip, and installing an IAT sensor (intake air temperature). Mine is installed in my K&N filter. Casper's electronics sells a kit that makes the IAT install easy (uses factory-style wiring, etc).
Oh also, another good thing about the 86/87 ECM is that if you ever decide to convert to electrical fans, the newer ECM have the ability to control them based on engine temp, which is nice.
If you haven't already discovered it, there is a section on this board specifically for us Hot Air guys, everyone over there is REAL helpful. If you search through there, there are about a MILLION posts discussing the 86/87 ECM conversion (its one of the most common things us hotair guys first do to our cars). There may even be a sticky about it. If you still have any questions, post a thread over there and some of the experts will chime in and really help you out.
Oh, and welcome to the turbo buick world!!! I was in the same boat as you, before this car, all I'd owned was older muscle: 67 Skylark (GS clone) with a bored-out 455, and older ford trucks. It took a while to get the hang of these "newer" cars with all their sensors, vacuum lines, etc. Read up a lot in the hotair section, read all you can on GNTType.org, and have fun! One last piece of advice, one of the best things I did when I got my car was to go through the rats nest of vaccum lines and replace everything i could. I found a LOT of lines cracked and brittle and leaking, and quite a few that were connected wrong. I think theres a sticky in the hotair section detailing the exact routing for all the lines.
