Couple of questions on May's night salvia.

1. When can I transplant them? I have to move some towards the back of my garden area, because I want to plant some mums in front of them, but don't want the mums to block the sun.

2. Deadheading- I've been deadheading them as the flowers fade and they've been coming back with more flowers but are bare in the middle. How do I get them to mound? AND, if I were to cut them back completely underneath the last bottom part of the leaves would they grow back more fuller?

3. Why is it that they seem to not flower the whole part of the stem? Top part, flowers more than the bottom part. Does the top flower first then, the bottom, or vice versa and I'm just missing the bottom part flowering?

Thanks for anyone's help in advance. This is my first year at gardening and I tried to pick items that would do well with or without my help.