Welcome! Great to have you!! Im not really sure what to tell you on the potty training! Not having much luck there myself!
But as far as the size, the breeder I got Kobi from said that he would stay small too! His parents were 5 1/2 and 4 pds. At 15 weeks he weighs roughly 2 3/4 to 3 pds! So Im really not sure what his final weight will be! From everything I heard and read its kinda hard to tell! Proly not very helpful but I just wanted to let you know that was my experience too!