Go to Ecruteak City and after u defeat the 5 kimono girls and talk to the man with the blue hair and a hat.
Hope this helped :)
If you can trade Pokemon from crystal version to gold version my guess is yes
Registeel doesn't exist in crystal version.
To trade Pokemon from Pokemon Crystal version to another version of Crystal you need to use a link cable. You can also battle this way.
Crystal version.
In Pokemon Crystal Version, a Heracross will occasionally appear when you use headbutt on trees.
Yes
in any version you need a masterball
Yes, yes they can.
Yes, it can, but only if you have the gameboy version of crystal.
At the Radio Tower.
yep
The strongest Wobbuffet you can find in crystal version are in Cerulean Cave, they might be a little hard to find though