I think these topics will answer your questions:
Catalogue of drive gearings
V5: Drivetrain gear ratio feedback
Also, this post by @9MotorGang is a great resorce for Vex Fourm use:
PSA to new forum users v2
Finally, for most things Vex that you may need help with, @Gigahertz.t’s post here will help you a ton:
New Team Starting Resources
Good luck!
Elijah Lim,
1417R RachmaniBOTS