Hey Chris, great to see you're interested in adding a ball python to the mix. I'll attempt to answer all of your questions to the best of my knowlege.

In my experience, there is not a problem keeping snakes and rodents in the same room. I do this with my snakes and haven't noticed anything crazy happen.

I think it actually could have some advantages if you are planning on feeding F/T. Firstly, you could pre-scent the room by scheduling your snake to eat on the same day you clean your rats' cage(s). A lot of times this will stir up some extra rat smell, and it's possible your snake will notice. If I were you, I would thaw out your feeder rat, go clean your rat cage, then try to feed your snake. Another thing you could do with the frozen rat is add some extra rat scent to it by putting it in a sealed container of used rat bedding.

As far as I know, there won't be any psychological problems with having a beardie and a ball in the same room in sight of each other. The ball will most likely be spending most of his day hiding, saving exploring for night time while your beardie is dozing. I also used to have an adult beardie in a room with many snakes with no apparent ill effects.

The electricity needed to keep a ball python should be very low, depending on what kind of set up you would like to have. Using a thermostat (which is strongly recommended anyway) will further reduce electricity usage.

Even adult ball pythons usually only cause minimal damage if one happens to tag you. It is when and if a snake actually holds on and coils after it has struck you that any really painful damage could occur. This has never happened to me or anyone I know, so I'm not sure to what extent of damage it would really cause. I have however been bitten and coiled on by a baby Burmese python, and that was quite painful and left a lot of bruising, but nothing serious.

You can expect to take an otherwise apparently healthy pet ball python to the vet for a yearly physical exam and yearly fecal exam. Exam prices vary from vet to vet, but I would "guesstimate" somewhere between $40 and $70 for a physical exam. With the right set up, your snake should stay healthy, but respiritory infections are not uncommon.

As far as male or female, I don't notice much of a difference between the two... if you think you would ever plan on breeding I'd go for a female first.