A great site for yokomo tech is
http://www.rc10talk.com/index.php Just navigate to the yokomo section and you will find loads of great posts.
As for batteries, I am using Trakpower 3200 lipos (in my works 91), they fit really well and dont require much modification to the battery posts but you will need a lipo charger.
Here is good link for all things motor's
http://www.hobbytalk.com/bbs1/showthread.php?t=126994