16 gyms 8 in johto and another 8 in kanto.
16
Yes, you can fight the Kanto Gyms in Pokémon HeartGold.
Beat all 16 gyms.
In almost all of the towns/cities.
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
You get rock climb at the one of the gyms
he's in the cerulean cave after you beat all the kanto gyms.
Most Hm's are located through gyms or the story-line of the game.
after you beat kanto gyms prof. oak gives it to you :)