I'm so used to playing the vanilla game in a way that avoids the bugs that I can no longer remember all of them. If you check out the main page to MM7, you should find a link to Bones Combat Guide to MM6, which should answer a lot of your questions on fighting. Unfortunately, there was a server mishap early on, and all the back files behind Redneck's MM6 site were lost, so much very high quality work behind the game is no longer available, and only the Tavern remains. TEF's (Tennessee Ernie Ford's) site was also very good, but that too has gone to cyber Valhalla. And of course, the official 3DO site went when 3DO went down the tubes.3DO's first official patch (from v1.0 to v1.1) cured a lot of the original bugs, of which the one most often referred to was the Gharik's key bug. That was a problem that the key to Gharik's Lab vanished after it was used, and if you left the dungeon and then returned to it afterwards, it reloaded with the door locked and no key. The easiest way round that was to use Elrond's editor to get your party another key, of course.
The second official patch (to the v1.2 game) cured that, but left two doors permanently locked, one in Castle Kriegspire, which barred access to the jewelled agg so you could not complete that quest - but that was no more than a local quest. The other door, IIRC, was the one at the back of the entrance hall of the Shadow Guild in the Frozen Highlands, which prevented you from exploring the rest of the building. That was only important if the King of Thieves escaped from your custody while you were taking him to Lord Stone; if that happened, he would go to ground in that dungeon, which would make you unable to complete the cleric to priest promotion quest. We constructed a "fudge" fix for these, by temporarily reloading the v1.1 game for those two quests, and switching back to the v1.2 when those dungeons were done.
Those were fixed by Mok's (unofficial) patch, which also made the game engine compatible with WinXP in >95% of cases - a lovely piece of work.
There are other patches and mods, notably Greyface's and the work done by BDJ and his team to construct The Chaos Conspiracy, but I've not played any of these and cannot comment of my own knowledge.
The "features" (beneficial bugs) allowing druids to learn mirrored path magics and giving characters access to weapons and armour that they should not officially be able to use were fixed by the v1.1 patch.
