I have the 1500 which I also purchased from All Brands. The feed dogs go all the way down. I have it doing FMQ right now and I can't feel the feed dogs at all when I run my finger over them.
The FMQ foot that came with mine is all metal. It was a closed circle which I hated so I cut the front of it open to make a nice wide C shape. This works much better for me. My FMQ was horrible for a long time, but I had never done it before. It's passable now so I assume the problems were me, not the machine.
I have had no thread curling issues. I use only 2 or the 3 holes in the top thread guide. The only threads I use are cheap. Coats and Clark, giant cones of serger thread from Joann's.
All in all, I love this machine.