Hi The least you should do in your case , is use liquid Waterproofing Membrane ( look at your local flooring supply store) it is kind of heavy and shipping cost will be too high, What I would recommend you to do is to mix a scup of no 20 or 30 sand with a 2 gallon of the liquid Waterproofing Membrane, it should give you great protection and easy to apply tile on. A product I am familiar and recommend is pro red by c-cure ( link to c-cure pro red attach) I would not recommend sheet membrane, you will need to know how to use it in/out side corners and overlapping and making sure it seal well., a risky way for leaks. The liquid apply same as you paint 2 heavy coat will do the job. Never heard of Hydraflex, I will check them out Here is a link that might be useful: C-Cure pro red

I used to live in Austin and desperately needed a softener there. We were concerned about that slimy feeling too, but you can control how much salt you use and we couldn't even tell we had one. It made a world of difference in everything else though. You can also look at water conditioners. People swear by them, and with one, you don't need softener. I'm still trying to figure out the pros and cons of each.

The first is to consider what the value of your home is and the comparables in the neighborhood. Determine your equity next and the cost to renivate. Then think how long you plan to stay in this home or would it be wiser to find another home that suites your needs? Alot of things to consider that impact this decision. Best wishes!

Cannot answer that unless you provide us with the distance.