>If I use a Using/End using block and inside I have a Try/Catch which could return False, will the Return False affect the End Using? In other word, will the End Using always be done if I exit this block before it reaches the End Using?

Remember that a Using block is compiled as a try/catch/finally block - so the outer finally will always execute (and Dispose() will be called) even when an exception occurs in an inner try/catch.