The FG is a smaller version of the earlier FM/A's. Will it take better pics than digital? If you gave different pots to 2 different cooks, would one produce better dishes than the other (IOW, it's not the gear, it's the photographer). Can it do better than digital? Maybe, but you need it perfect working order & with a great lens on it, plus Pro-grade slide film before you'll know.
A new battery is probably the least it needs, the shutters may be frozen, but you'll never know unless you can clean the contacts & power it up correctly. I wouldn't waste too much time on it myself.....I've found Digital to be so much cheaper & better in the long run, that paying for film processing isn't worth it to me.
The FG shold have a 1/90 the manual speed.Look on the right side as you look through the lense there is a dial where the film winder is, should have a "A": and 1000, 500 etc and a 90 and the 90 is a different color. Set the dial there and you shouldn't need to get a battery to test (of course make suer the lense cap is off)
BTW this is a manul focus camera, no auto, and no auto wind either
Will it take better picctures than a digital? A good photog ccan take good pictures with anything. That said a 35mm image scanned at 4800 dpi give you a file 7104 by 4560, thats 32 mega pixels