gryphons are in select cities to fly to other cities with flight points. when you are in a major city, talk to a guard and ask for a gryphon master. if you dont have a flight path, it has a green ! above it's head. there is a gryphon master in ironforge and stormwind, also in other towns/cities/camps. not everyplace has one. gryphons arent a type of thing that you ride around and attack with, they are just for transportation. it costs money to use them. they are very useful. they dont fight at all, unless you attack the opposite faction's wyvern/bat master and he summons them to protect him.
yes hunters can use guns, bows, and even crossbows. to learn hwo to use a gun you must go to iron forge, ask for a weapon trainer, and you have to pay 10 silver to learn how to use guns, then you can use them. if you are a dwarf hunter you can automatically use guns, if you are a night elf hunter you have bows, and you have to travel to IF.
my question to you, are you going to go dwarf or night elf? night elf is harder to learn guns because you have to travel to IF, but bows are just as good as most guns. as a dwarf, you will already be close to iron forge, you wont need to buy gun skill, and you dont have to spend a while to get to iron forge to learn it. your choice.