What you mentioned are fairly straightforward changes. You can search on topics to see a lot of discussion about how some of these are done.Mods only work on single player, TCP/IP connections and (I believe in some cases) open battle.net...and anybody joining your game needs a copy of the mod too. You cannot play Blizzard realms with a mod. There are projects underway to make Realm-type servers for mods. But it is easy enough to set up a number of mods and still have vanilla D2 at hand too. This thread discusses one way:
http://dynamic2.gamespy.com/~phrozenkeep/ubb/Forum29/HTML/002740.html
Also verboten is bringing a mod character into a different mod or into unmodded D2, or bringing an unmodded character into a mod game. You >might< get lucky. On the other hand, you might crash, or find your character newbified (in which case you better have backups).
[This message has been edited by Myhrginoc (edited 08 February 2002).]