Firstly, welcome to the forum. Don't be afraid of, what to you, may sound like silly questions. We all had to start somewhere, and we're here to help.
Now.... as to what to look for.... A new battery will be a certainty. If it's stood for five years without charging, it'll be dead, dead, dead! If it's been in one place for all that time, the tyres may well be out of shape, and need replacing. The fuel in the tank may have gone bad (change it, anyway), and there may be rust in the tank. The carb is the Achilles heel of the GZ (we always advise using a carb cleaner in the tank every three or four fillups) so the carb may need stripping and cleaning. You'll certainly need an oil and filter change, and a chain clean and lube. A valve check and adjustment is to be recommended. If all the above needs doing, I reckon on about $500 for the shop to do it. One more thing has just occurred to me. When you get the new battery, buy a battery tender at the same time. The battery needs charging at no more than 2 amps for around 10 hours, before you use it. No matter what the salesman says, we know from experience that if you don't charge it, it'll not last very long before you have to buy another. I think I've covered everything, but if I haven't, I'm sure someone'll come along and fill in the gaps.
Something else I've just thought of
. I've been riding for fifty years, and I won't ride without crash bars (what the Americans call engine guards). Everyone goes down at some time in their riding career, and the last thing you want is a leg trapped between the road and a heavy, hot, engine. Last time I went down, the bars got bent, but my leg survived intact.
Well.... Good luck with you bike, and if there's anything else, just ask.
