Personally I do think it is a small cage for a senegal. When I move into our bigger place, my Senegal will probably be getting my red bellys flight cage, which is 32 by 21. There should be enough room for at least 4 different perches, all different widths, and only one should be the sandy type. It depends on how much out time the bird gets though, for some people a small cage is just for sleeping, then the bird travels with you or is on a play stand all day. But if the bird is left in the cage a majority of the time, the ideal thing to do would be to get as big of a cage as you can afford, that is appropriately sized for your bird.
The hanging thing looks abnormal to me, but some birds can do it a little, just not all the time. It could be a sign he has no where comfortable to perch.