Congratulations on your new Princess!
I don't know why your vet would advise two separate surgeries, instead of spaying and retained baby teeth removal being done at the same time
It only makes sense to do both, and have to put her under anesthetic the one time. I would insist both procedures be done on the same day, and if the vet refused I would find another vet.
Below are some links about current vaccine protocols. But, your vet is right, typically rabies is given around 6 months of age. Please do read though, because it's also important to know vaccines should not be given all at the same time in the future.
http://www.yorkietalk.com/forums/yor...-overview.html Dr-Dodds-ChangingVaccProtocol
Also before her spay/teeth removal have pre-op bloodwork done. The bloodwork results can be an indicator of any issues to be aware of before being placed under anesthetic.