Hi Ari, I think your approach is rational, but in practice involves a bit too much light.
for starters lets talk about the grungy bathroom look.
typically the best way to achieve this is to actually not use proper kino flo bulbs but rather normal household flourscent "cool white" bulbs with a lower CRI (color rendition index). What this does is gives you a more monochromatic blue look which will help with the grungy look. If these bulbs are in frame you will probably want some additional light to combat the brightness that looks like it is coming from those in frame sources but is actually out of frame so the bulbs arn't super blown out...however if there arn't any bulbs in frame for a large bathroom space even in a huge wide you probably wouldn't need much more then 6-8 bulbs to achieve a 4/5.6 at around 400 ASA
If there are standard overhead fluro fixtures in the ceiling a very popular thing to do is to take newspaper and hang it down around the fixtures to keep the light from hitting the walls. This way you have a nice grungy soft top light but your walls stay dark. "grungy" I think is generally a mood achieved by low key lighting which means that you will want most of your frame a bit underexposed....maybe even your talent a bit underexposed too or just a portion of them lit to exposure.
Your next thing to think about is how powerful you want that disco light effect to be. If you want it to be pronounced your in a situation where you probably want the bathroom to be really underexposed else how is that disco light going to show up? you will be in danger of over lighting. However if you want a more subtle effect I think you could get away with having your bathroom a little more near proper exposure....if you want that disco light to show up strong I would think you won't want much more then 2-4 tubes lighting the whole space.
as for the flicker....you can try to put the fluorescent's on dimmers but I'm not exactly sure how it will react sometimes that works.....it is also bad for the ballasts so maybe use some household fluorescent casings which you can get a home depot or other store like that.
For the disco light assuming you want a real disco ball look with the spinning reflections I would recommend using a real disco ball. A disco ball is just a spinning set of little mirrors on a ball with a light blasted at it. so I would do just that but you can use your own film lights to put on it. Im sure others will have more experience with this...I have never had to do a disco ball effect. But maybe even have a couple tungsten heads on dimmers with different colors on them and fluctuate them if you want changing colors....I would probably just pick a single color myself.
I think if you want to have a more beauty/stylized approach you could light your talent on top of all of this. possibly motivating rim lights or something from the grungy bathroom fluorescent or disco ball. But honestly you have enough light already. I would suggest maybe just having a couple more cool white bulbs in a kino or two (or your own diy) housings with some Diffusion on them that you could move around on stands that you could use to supplement what you have already put up.
Generally disco balls are white light. So if you use a non gelled tungsten light for the disco ball (an white balance at 3200 for that) and then light the bathroom with cool blue tubes you will certainly achieve your grungy blue look.
Best of luck