I can say in regards to size.... The pink sweater fit Bevo and Mack perfect..
they generally wear a x-small to small in store bought clothing and weigh approx 6 pounds... The medium we tried on our morkie (who likes to go naked) for sizing and it fit him well on the tummy... Was just a bit long... He is about 7 1/2 pounds... He looked stinking cute in it!! Whenever I can actually find time to sit at a real computer and not my phone, I'll try and post pics!