does adding bigger tires to planes make a big difference in the way they fly i have to take off on fairly tall grass most of the time and bigger tires help say if you go up from a 3 inch tire to say a 3 3\4 or 4 inch does it make too much of a difference?

Not alot of difference in flying but it does give better performance in grass.
I put bigger wheels on alot of my planes because we fly off a grass field.
Trike gear try to increase all wheels by the same amount.
Tail dragger, try to raise the tail by at least half of what you raise the mains.
If you have wheel pants they prorbably wont fit with bigger wheels but wheel pants aren't good in grass anyway.
Make sure to check the balance after making any changes.

as far as i know - no, they add a little weight and possibly a tiny amount of drag but it is not noticeable

as said above, i put 3" wheels on my trainer and it made a fair bit of difference when flying off grass, much better!

I only use 3" tires on my planes due to a rough field. I just put together a great Planes Reactor and it came with tiny 2" wheels. It never would have been able to move at our field. I use at least a 3" if not bigger depending on the plane.