hey,..
for me,
your bike is too long for flatland...unless ur as tall as trevor MEyer
to ride a 20" frame in flatland..
anyway...
it doesnt make any BIG DIFFerences when you ride big or small tires..
i suggest 1.95....its good all aroud..
for fork and bars,just buy something thats comfortable..
later on when u've practiced a lot, you'll know what to buy.