my daughter was going to mail a bubble envelope to a friend. She found out the friend already had what she was going to mail.  Is it ok for me to use the postage stamps that are on the envelope??  

I personally would say yes Bertie.  You have purchased a delivery service that has not been used yet.  Some postal workers may disagree with my opinion tho.

Well I'm a postal employee, and I say.....you're right!

I had to cut the stamps off the envelope so I will have to glue the whole thing on to the package I want to mail. Will it still be okay???

It should be.  Just don't put tape OVER the stamps themselves.  The worker must be able to cancel them.

I am a window clerk for the post office, you need to cut as close to the edges of the stamps as you can and then use glue or glue stick to adhere them to the package. You DON'T want it to look like you just re-use some stamps that you got in the mail that didnt get canceled, thats why its important to cut as close to the stamp as you can :)