I won't have time to test every point until the deadline, but here are my results:

a) Terrain clutter corresponds to the visible terrain layer (e.g. grass appears on dirt, not on lava). 

I spent some time on Drakul, and no grass on the volcanic areas. None at golem areas in Mithril Anvil. 

b) Footstep sound (Bipeds only! Sorry, dragons!) should always correspond to the type of surface your character

Not tested (only played my Dragon) 

c) Intense combat does not crash the client. 

I didn't notice any issue from this side. However, I haven't spent several hours of really intensive hunting. But well, no crash to report.

d) The loot window should allow looting, both with and without using "take all".

It works fine.

 e) Run through some quests and verify that the NPC hilight and step expansion work as expected. Also try unusual things like recalling in front of the NPC you need to talk to to progress the quest, as well as deleting the quest

Not tested, sorry. 

Otherwise, the client was stable during my playtime, I didn't notice any specific issue compared to previous one.