Is there a plugin that...

I need to know if a few plugins..

it would really help me out
-Ability to force a player to do a command while stepping on a specific area (if they have the permissions of that area)
-Ability to buy permissions for a specific user.
-Ability to force a player to have specific inventories in specific worlds and forces them to not drop items.

ALSO! looking for some volunteer java devs, i will repay with rankings!
i just need some simple plugins

Thanks
-TurtleKing