You're right, indeed low-res is enough.
I actually have some problems about that: most of the time, the inventory items gfx I grab are 46x36 or 42x44 or whatever. I made the choice of resizing them (nearest neighbour) to 32x32 (in order to put them into RTC), but it's of course not the perfect solution. I also made the choice of suppressing shadows for items in inventory, that's another difference between BC and DM...
Here is what I have made by now, including the final graphics and the screenshots:
http://wtrns.fr/9pdae1dE51AXgHg
I also have some videos for the creatures sounds.
Note that the link will die in 2 weeks. I'll post the final gfx+sounds folder when I have it...