Welcome from BEST to Vex.
Yes you can use EasyCV4 to program your robot.
Each HS/MS (non-College) team can only bring 1 robot.
If you have registered multiple teams in the same family, like 126a, 126b, then each can bring a robot and play independently.
BEST has rule of 24x24x24"x24lbs.
Vex has rule of 18x18x18" size only, any weight is allowed.
So you can build any form you want that meets all the other rules;
(see inspection guidelines section of the rules)
you are not restricted to just a tumbler or protobot.
After your initial bottoms up brainstorming,
try browsing this forum for threads with links to pictures and youtube videos to see what others have already tried, and how well it worked.
Thanks for the info. Say I build two types of robots for one team, can I use one kind for one round and another for the other round?
I got a disc called Auto desk EDR is that for programming or just to make sure your parts work before building? I am used to Easy C4, but which one is easier?