new setup for active to active clustering

HI,
I'm going to setup active to active cluster on win2k3 and sql2005,with centralize storage SAN. since i'm new in this env and ust read document on cluster. i've some doubts and need ur assistance
1- how many san disk require (read some where that each intsnace need dedictaed shared layer --not sure)
2- Do in need 2 quorom since there will be 2 active instance
3- how many total group I need for 2 instances and what will be in each group
4- what about MSDTC, DO I need it and where it will be installed
what else do i need to consider or any advices
thanks in adv,