RE: Projects - SL 2011 SP2
The user guides are pretty well written as far as user guides go - albeit a bit dry.
There should be some eLearning resources in your CustomerSource you can use to get the basics of the Projects module.
Your VAR should be able to help you with some training and would know how to handle the "different way" you are using the module.
As far as your question goes, you can either give each person a sub-account and manage their budgets outside of projects through the financial modules, or use projects and the budgeting functionality it offers.
It's another "it depends" answer based on what exactly you are budgeting and how detailed you are trying to get.