Upgrade SEP from 11.x to 12.x

Hello Evesybody

My company going to upgrade curent SEP from 11.x to 12.x. So, I have any question about this issue :

1. Please give to me document or share link how to upgrade ? (more detail is better).
2. we have around 700 SEP client . which should used database better ? (Embedded database , SQL serve 2008 Express or anything,...

Please give o me your advise

Thanks and BR

phamduyus