#1
I have a question about starting and ending a phrase on a chord tone.

Say for instance you are soloing using the A pentatonic in the Key of A.
Your phrase starts while the A chord is being played. You choose a chord tone from A to start your phrase. Does that mean the rest of the phrase you can use any or all notes in the A pentatonic as long as you end your phrase on another chord tone from the A chord if it is still the chord at that moment? And if the chord changes to say D in the middle of your phrase you end the phrase using a chord tone from the D chord instead?

Also in the middle of your phrase if the chord changes, does that effect your note choice from the pentatonic scale like focusing on the new chord tones on the down beats?
#2
There are no set rules. The starting and ending on a chord tone is a good idea when your just starting out with this sort of thing. However with your phrases yeah, you can use any notes in the given scale you are using. Your ear will guide you as to what sounds good. But, dont limit yourself by thinking I cant do this or I can do that If it sounds good to you then it is good. PM me if you want me to make an audio recording of me soloing over chord changes and this will let you hear what Im talking about better than me explaining it
Andy