16 gyms 8 in johto and another 8 in kanto.
16
Yes, you can fight the Kanto Gyms in Pokémon HeartGold.
In almost all of the towns/cities.
Beat all 16 gyms.
you keep on battling the gyms
Pokemon HeartGold, SouldSilver
Gold, Silver, Crystal, HeartGold, and SoulSilver Versions. They all have 16 gyms (two regions).
No, but you can challenge kanto gyms
he's in the cerulean cave after you beat all the kanto gyms.
after you beat kanto gyms prof. oak gives it to you :)
You get rock climb at the one of the gyms
Most Hm's are located through gyms or the story-line of the game.