Coring questions

Hi guys,

Was looking through the archives here for stuff about what kind of drill to use for coring, but didn't really find anything. Is there a minimum RPM I need to get in order to make a dry coring bit work well? I've got a large Makita drill that I use for mixing 5-gal pails of mortar, I'm hoping that will be powerful enough.
For now, all I need it for is to drill out a sink drain at the bottom of my hollowed out rock. Later, though, I'll be wanting to core through 4-5 feet of Stone (http://g603.net) to make fountains, etc. For this kind of work, do I need to get one of those special coring drills on the stand (http://maplered.com) s, or is it possible to keep using a hand (http://maplered.com) -held drill and (http://maplered.com) just buy long extensions for the bit? (which might make it tough to core a perfectly straight line through the Stone (http://g603.net) ...)

Sorry for the newbie questions - I've got lots to learn obviously. Thanks in advance.