lets say I need an extra 10 points for my reservation at a specific resort... can I simply pay/rent 10 extra points from someone? how does this work.... say the week I want at SSR costs me 220 points and I only have 210?
You would simply go on the DIS Rent/Trade board, agree on price and payment with another member, pay them, and they'd transfer the points to your DVC account by calling MS. You would have to do that prior to making your reservation, but if you use Paypal (or if they have the ability to take credit cards), it's a quick, easy process.
The other option would be to borrow 10 points from next year's allotment.