By and large no difference what methodology you are using. The agreement must specify: the subject of the development, stages, timing, cost, law... Everything else is not relevant to the contract. That is, you can take any contract for software development.
Of course, nobody forbids you to specify something in the spirit "while working on your project we commit ourselves to drink coffee and wear green Slippers", but why?
View the contract Lebedev Studio, for example — www.tema.ru/jj/RIBBA-sait-2009.doc
But in General, my personal opinion (not necessarily correct) that the custom software development to apply the so-called agile methodology is not necessary — the customer will fly with the money and jump in the middle of a project, because such methods do not allow to calculate the project as a whole (who knows what will happen in the next iteration: the news feed and integration with the SAP?). I would suggest in your case to do iteration (planning, design, development, testing) — individual projects (or phases of the annexes to the framework agreement), in the event of a breakup, no one was hurt.