I took both of mine to the vets the first day home just to be sure everything was ok.Lady was 7 weeks old when I got her and Jessie was just 8 weeks.They both had their forst shots at 6 weeks old and then every week until they were completed.
To change their food,you just have to do it slowly.Add some new kibble to their usual kibble and add a little more each day until he is totally on the kibble of your choice.Keep some nutrical handy too,this is to keep your new babies sugar level up and after the stress of the first couple of days its always better to be safe than sorry
Congratulations on your new baby