It is not too late to hand train your present bird. In fact now that you only have one bird would be a great time to work with her. Lisa has some excellent suggestions in her threads on training.
Hand Training a Parakeet -http://www.lisashea.com/petinfo/articles/bird_hand.html
Q&A on Hand Training a Parakeet -http://www.lisashea.com/petinfo/questions/q7
As far as the bath; you can mist her with warm water. I usually mist mine with warm water then I put their bath in the cage. That was the only way I could get a couple of them to actually get into the bath and splash around.
Their bird bath is also their seed holder, treat holder and veggie holder. That way when I put it in their cage they are quite familiar with it and it does not scare them.
Cage setup is really an individual thing. What I usually do when I am thinking about changing their cage is sit and watch them for a long time, paying attention to where they go and how they get there. Then after I change it I watch also to see that it is working for them
When you get your new bird there should be a 30 day quarantine to make sure you are not bringing any infections to your present bird. During that time you new bird will get quite familiar with the part of the house he can see.
You are allowed to do anything you think is good for your birds.
It is always good to have at least three different types if perches in your birds cage. I have two wooden perches that are not just the straight dowel type, but have differing widths. I have two cement perches for their talons and beak. I also have two rope perches. My guys LOVE their rope perches.
I kind of rattled on a bit. Sorry