I know I should know this, but...

there's not a "varispeed" function available in sonar, so yes, when you stretch them they will remain the same pitch.  sonar's stretching capabilities will not affect the pitch, they are time based only.

in order to change the pitch, there's a pitch adjustment plugin available but it's not great.  a lot of artifacts will likely be audible.  you can use v-vocal to change the pitch and that might work a little better, but since you're not working with monophonic tracks, it too, will likely have problems.

someone else might have a better answer for you, but that's the best I can come up with for your situation.

Once again I recommend using other software for this task, Sonar is awesome multi tracker, but is not a very good wave editing suite. Wave Lab will do what you wish.But if you can't afford it then there is also a workaround with a free download DJ program that will instantly change either or both pitch and time. Virtual DJ. It's a heap of fun to play with anyways. But you will need to record it via "what you hear" with the free version. .......... http://www.virtualdj.com/download/free.html

>>Load the file in to a sampler, set the key mapping so the root key is E and hit Eb. Instant half tone slowdown. Child
>>

Dude, you rock!

I'll give it a try.

-Jack