I hate to be a pest... but it just needs to be hammered in, because the statement:
'I don’t like the fact that this program does not allow you to assign keys.'
is so weird.
See the controls button on the main menu? From there you can assign any key you want to whatever function you want
If you need further help, there is a Help button on the main menu as well, it explains everything you would ever need to know about the menus, the controls, and the game
As to stylus control versus dpad control, it depends on the user, I've seen about a 50/50 split between gamers that prefer one or the other.. so try both and see which suits you better. ( I guess its similar to goofy-foot versus regular fot with skateboarding/snowboarding