I'm no expert but currently have far more free time than Wolf, but from what he has said so far, at least what i remember of it...
-horses- I dont recall anything said of this.
-carts- He mentioned the summoned minions or demons can be used as pack mules I believe.
-Safepoints- If it's like Teudogar, and I think this aspect is, you can take over virtually any non-plot-essential homestead. When doing so you gain the owner's slaves as your own. These slaves will produce you goods. And again if it's like Teudogar, and this aspect probably is, if you leave your items in someone's house, you can always come back and get them without stealing... er... I think...
-customisable colors- on your characters, usually this is only an option in mmorpgs, in single player crpgs you can simply change settings on your moniter to change the colors of your character
(I don't recall mention of selecting race, but there was some mention of vocation i believe, let me look back at this.)
-Inventory- I think in Darghul you have a permanent bag, and you may pick-up other bags also...
He speaks more detailed about this here-
http://www.darghul.com/newe.htm
http://www.darghul.com/darg14.gif
The inventory system seems to be highly influenced by Ultima Online's, I really like this inventory system, far better than any single-player rpgs i know of.
-destructive environments- I think the challenge here wouldnt be so much the coding as the new tiles and animations, another problem that would be posed is if you can burn down a village someone can burn down your village, and you would have to have a way of re-building, which would be even more work to implement. Or even the npc's rebuilding. Some villages come pre-destroyed for your exploring pleasure
http://www.darghul.com/darg05.gif
-Terrain-
http://www.darghul.com/darg08.gif
Although, there are hills in Darghul, I doubt the game knows it, this is probably an illusion the tiles create. Fire wouldn't be easy to program or draw, also using fire tactically wouldn't be easy. If you were in a field and the enemy in a forest, setting a tree on fire would sooner burn down the field than the forest, also you would have to be verrrrrry careful with your magic if fire spread. lol
-weather- Currently, from my understanding, weather is... Clear and Sunny, or, Raining.(sorry had to use bad grammar,'not that i havent throughout the rest of my post') There has been talk of Snow but currently no intention of implementation.(errrrrrr, I think) these being the 2 weather conditions, you would have to assume it's always warm outside.
Well, I tried to restrain my sarcasm and negativism, but apparently I didn't do a very good job. Maybe when Wolf gets a chance he will give you a real answer, but until then maybe this can make you think, whether or not it does any good.
I'm going to browze through his old posts and see if i cant find some references.
-well, i tried to make a list of citings twice and i keep getting power surges, reseting my computer, just browze through here.
http://www.rpgcodex.com/phpBB/search.php?search_author=Wolf+Mittag