Bringing home a messed up dachshund?

tomorrow i will be recieving a dachsund who is special needs to say the least. he is just getting over kennel cough and is extremely thin he also has a problem with his back legs due to being confined in a tiny area (i think). i have made him a vet appointment and am prepared to deal with all of his issues. he is only 6 months old so i'm hoping he will bounce back quickly. my biggest worry now is that i've never had a little dog before! i currently have two large dogs and i really need some tips on hadleing dachshunds. i'm planning on feeding him royal canin dachshund 28. but what sorts of temerment quarks should i watch for and things like that?