Boost gauge's aren't really necessary until you start modifying... with a stock motor running stock boost pressure it's kind of pointless. BUT, once you start mucking around with things you'll want one, and they're relatively inexpensive... so it couldn't hurt to throw one in there. Stock boost gauges on most cars that come with them *cough* 300ZX *cough* are really innacurate and would need replacing once you modify anyways. But as I mentioned in my last post... suspension/brakes are first, then power.
As for special attention for your turbo... compared to a N/A car. Change the oil regularly. (how many miles are on your motor?) Switch to a synthetic oil... mobil 1 and Redline is what I use. And maintain as necessary. It's really not all that much different. Be sure to (if you can) let the car warm up before leaving in the mornings, and when you park the car after driving (ESPECIALLY if driving hard) let it idle for 1-3 minutes before turning it off.
(which is what a turbo timer will do for you, so you don't have to sit in your car and wait)