Grounding to the same ground point is generally considered a good idea. Make sure that ground point is a *good* ground point with a good return path to the battery.
I've heard both ways on the battery - yes and no, but in practice I've seen many installs where people ground directly to the battery and haven't had any issues. Where you may find a problem is if you have equipment this is NOT directly connected to the battery and is grounded to the chassis. If the ground connection is a higher resistance than your battery connection, it is that differential that creates the opportunity for a ground loop.
As always, make sure you fuse the battery connection within a foot of the positive terminal to protect the battery if the cable accidentally grounds, and fuse again near your equipment to protect the equipment. Check the FAQs in the nav bar for more info and also visit the FAQ Emporium forum for additional FAQs in the sticky section.