No.
Poke'mon Master
I'm afraid that you cant make or get Pokéblocks on Leaf Green/Fire Red
shoot him with a railgun
only firered and leafgreen.
No these two games are already remakes of the original red and blue version there not going to remake firered and leafgreen.
No two Pokemon make mewtwo ,you must catch it in firered or leafgreen and if you want you can migerate it to diamond or pearl.
contest hall
You can't capture Arcanine in Leafgreen. You will need a Growlithe from Firered first then use a Fire Stone on Growlithe to make it evolve to Arcanine.
If you put Soothe Bell on a Pokemon or give it Pokeblocks.
You can make pokeblocks at any contest hall i would suggest blending berries at lilycove city's contest hall.
Feed it Pokeblocks and make sure it doesn't faint in battles.
Just like in FireRed/ LeafGreen versions, you must have 7 badges.
Pokemon can only have a set number of pokeblocks. Once they have eaten that set number, they will never be able to eat any more. The only way that you can get your pokemon all the way to the highest amount of a skill is to make really good pokeblocks.