what OS should I use on an IIe hard disk

["Robert Collet" <collet@worldnet.att.net>]

First some background:

    The guy I worked for this summer used to teach electronics at a public
school and was like their main computer guy. Consequently, he knows just
about everything about the IIe. Anyways, we used to talk tech about the IIe,
and he would every once in awhile talk about his apple II setup, which
included, among other things, an 80 meg MFM hard disk and "enough memory  to
run appleworks completly from ramdisk" However, at the time he was living in
temporary residency and left the IIe back at home.         Well, yesterday I
found out he was moving up perminently and offered to give me all of his IIe
stuff, which he said comes to about 1000 pounds :).(when I get all of this
stuff, which might be as soon as this monday, I'll post a summary of it)  Of
course his setup will replace the IIe I use, and I plan to put all my games
and whatnot on the hard disk. I know that I cant use  DOS 3.3 (which most of
my games use) on a hard disk , so I guess I'll have to use prodos.
    I read the FAQs but I still have a few questions:
1. Whats the best  version of prodos for a IIe?
2. Generally, how compatible is prodos with dos 3.3 ,especially games.
3. Can I run prodos programs from a GEOS environment? if not, is there any
GEOS or GS/OS type GUI that I could use?
I dont know if this is the right place to ask, but I do have a spare
internal MFM hard disk that looks like it came out of a PC XT (except its
half sized)
I doubt the hard card for the IIe can be plugged directly into it, but are
there any schematics on how to plug an internal MFM hard disk into the
external plug?
 Thanks in advance