Yes, you'll be fine. I have two in my 34 gallon, but they don't hang out together all that much. I can't say if they'd school in a 180g or not. I lose mine from time to time in my tank, so you may not see yours all that often.
They don't really school. They cling to the rocks most of the time and usually right next to one another. You can get them to pair up or be comfortable in a small group. But be careful, they can become territorial with each other. Best bet is to quarantine them together and see how they get along.
there are very few marine fish that will school. some will shoal, but gobies are not one of them. Gobies have no swim bladder, so when they are in open water, they dont float, hence why they have a fused pectoral fin that is used like a suction cup too help them cling to rocks, sand, glass, ect...
while neon gobies dont school, nor shoal for that matter, they may hang out together. IMO it would depend on the tank size, and if they form pairs (ex, if you get 3 and a pair forms, then the third will be chased from the territory). I would personally get maybe 5-6 and let them form pairs. a 180g should be big enough for several territories.