Once you have the bypass in place so you have water, then the next step is to figure out what you currently have in place. I doubt you have three softeners - you could have a sediment filter, iron fitler and water softener, or any number of combinations of treatment. Take some pics of what you have and post them. Find any labels and post that information so we can try to determine what you've got. Are you on city or well water? Do you have the names of the previous owners so you can ask them what is there? Perhaps your real estate agent could help. It is a good idea to have a local water treatment pro out to take a look, do some analysis and make recommendations. If there is a sticker with a company name on any of the equipment, that's a good place to start. A three valve bypass looks like this:

There are basically three methods used to mount the angle stop valves. 1. Solder type 2. 1/2"NPT Thread mount 3. 5/8" compression mount. In new construction the angle stops are generally installed during the final trim out phase of the plumbing, which generally occurs after the painting or wall finishing phase. At this stage there is a very high risk of causing damage to the wall finish if we were to install the solder on type or to solder a thread adapter on the stub out. For this reason most plumbers elect to use the 5/8" compression type which only requires a simple mechanical connection. To install the compression type angle stops the stub out is cut to the desired length, then the compression nut is slide on the stub out, followed by the brass ferrule and finally the valve is slipped on. With the valve held firmly in its final location, the ferrule and compression nut is then slide out to the valve and tightened finger tight. Once the compression nut is finger tight the plumber uses two wrenches, one to hold the valve steady while the second wrench is used to tighten the compression nut. As the compression nut is tightened the inner brass ferrule is slightly compressed into the wall of the copper pipe thereby locking it firmly in place. When changing compression mount angle stops many people make the mistake of attempting to pull the ferrule and old nut off the copper stub out and usually in doing so they distort the shape of the copper making it very difficult to get a tight seal with the new nut and ferrule. A much simpler and more reliable method is to unscrew the compression nut then slide the old valve off the copper pipe leaving the original ferrule and compression nut on the pipe. You then remove the compression nut and ferrule from the new valve and slide the new valve on the pipe, tightening it in place with the original nut. While this method does not work 100% of the time, as a rule it will work most of the time and certainly bears trying before you begin cutting the pipe or trying to remove the old ferrule. When tightening the compression nut you can use a pair of channel locks to hold the valve steady, but when doing so be sure to pad the valve with a rag first so the teeth of the channel locks does not scratch the finish. I find an open end wrench to most convenient to tighten the nuts in a tight space. (I especially prefer my Craftsman ratcheting open end wrench.) When selecting angle stop valves I use the solid brass 1/4 turn ball valves exclusively. The ball valves have the advantage that they are quick acting full bore valves and they are also have the advantage that when turned they are self cleaning which is a distinct advantage in areas where mineral scale builds up on internal valve parts. I will probably open a real can of worms here, but My first choice of supply lines is chrome plated brass tubing with the cone washers that come supplied in your faucet set and the compression nut and ferrule that comes supplied with your new angle stops. I have seen copper or brass tubing supply lines that have been in continuous service in commercial applications for 20 or 30 years and they still work fine. My absolute last choice would be the stainless steel brain lines. While the stainless steel braid gives the illusion of being some kind of high tech space age strength and durability in the final analysis many of those lines are the absolute weakest link of all the choices. It is true that the stainless steel braid will prevent a line from blowing out, but when we consider that the maximum allowable line pressure is 85psig, the chances of any lines actually blowing out is slim to none. On the other hand, what most people don't know is that a vast majority of those stainless steel braid lines has nothing more than a stainless steel braid over a cheap neoprene hose. Under certain water conditions neoprene has a relatively short service life as is evidence by the failure rate of neoprene toilet flapper valves. In regions where they have problems with the water deteriorating the neoprene I prefer to use chrome plated brass lines with the factory preformed cone washers that are made out of nylon.

OP here. Haven't had a chance to read all of the comments--work 2 full-time jobs and am stealing a few moments from day-job 1.. But just got off the phone with a member of the tile association referenced by CT and they said to do the same test he said to do from get-go so will do that when I get off of work. My electrician "friend" is picking me up so I'll have to go on the down-low, lol. Sophie, you are on-point and Joseph--more power to ya! On a serious note, water isn't visibly coming down--but it's an old house with layers of plaster so may be taking its time. When water was coming down, I smeared some pre-made grout along cracks in the grout b/t wall and floor and water stopped. Been about a month or 2. I started this post b/c I noticed that ceiling's plaster was cracking more and spreading more and a piece of plaster fell down so thought problem was starting up again or had never been fixed with the premade grout. I have more time tomorrow to devote to this so that is when I'll read over everything carefully and pull out the contracts. Really, really appreciate all of you. No longer feel alone.

That is good news! Hope you got a better deal because paint alone for that house is going to be $$$$ as I'm sure you know, to say nothing of the labor, scaffolding, caulking, etc., etc. Huge job. I figure it will take a crew at least 2 weeks and possibly longer to do that job, depending on how many people they put on the job. I would ask for a "plan" because if they separate it into "sections" and they have more than one painter, it will more likely ensure an even application/look at the end. Each painter has his/her own "touch" on amount of paint applied and overlapping to ensure coverage, etc. Good luck. Make sure you get test panels made so you can move them around in the various light conditions during morning, afternoon and evening. Also you a flat finish with very good quality paint. It will last a lot longer.