A newbie with a cool idea

[MrBigzy]

1. Pretty much just Blender.

2. It's generally done by trial and error, though you could use the grunt as a comparison by loading his model in a CG program and seeing how tall he is in system units (can be cm or m).

3. There's no "limitation" to how big a map can be, but to how many polys are being rendered at once, how many recources are loaded (textures, particles, etc) and how big the render distance is (culling and such). Basically, do whatever you want and test to make sure it doesn't lag on a medium to low graphics pc (if you want everyone to play it). And make sure to add preloads in your scripts for particles and sounds to reduce lag.