For your first question check the FAQ Threads for more information
https://www.unix.com/answers-to-frequently-asked-questions/
Also i dunt think so what as you said the RH 7.2 and Proffesional resides on Price. Might have some diffrences. Because from what i know RH Proffesional is more up to Newbies entering Linux. Some of the apps wont be so called Critical and yes it have the Support features. For RH 7.2 the OS Mainly resides on Server based, Workstation and some advance feature (might be wrong, but basically it does).
For your second question, Search for Dual Boot
https://www.unix.com/search.php?actio...der=descending
Approximately 60 Answers for Dual boot can be find from previous members crushing their knowledge and sharing their ideas to make it work. Do make use the search facilities of this forum.
If you wanted or intrested in Unix, yes you can its really great to play around and fix and wreck things up with it. You may find it intresting too. Suggest if you can search the web or the best way Install and learn from Mistakes ( believe me i installed nearly 25 times on my PC and more then 45 times on my server just to install and bring the Systems up) at last what i gain ? Great knowledge and advanced ideas of Unix.
If you still kind find a good pointers, try starting from understanding Unix thru books or more best way is to search this forum..