Yeah it will work with the 4.0 branch no problems. Should there ever be any case of incompatibility I will create and distribute a new version and give to current customers free of charge.
To remove the thumbnail, this should work:
Open /skin1/customer/main/cart.tpl
REMOVE:
FIND:
Code:
<tr><td colspan=2><hr size=1 noshade></td></tr>
REPLACE WITH (remove the colspan=2):
Code:
<tr><td><hr size=1 noshade></td></tr>
Let me know if you have any other questions.