The standard Water Replacement Interval (WRI) in days for a spa is (1/3) x (Spa Volume in U.S. Gallons) / (# of Bathers) where the soak-time is usually 20 minutes or so, but that's for a hot (104ºF) spa. For a pool, you could go 3-6 times longer depending on temperature so let's say 3 times for your pool. If one person uses the pool every day for one hour (so that's the factor of 3 we're assuming for equivalent hot spa use), then we have (1/3) x (3000 gallons) / (1 person) = 1000 days or 2.7 years. If you are using this pool with more people or for longer than an hour per day, then the water would need replacement sooner. 95ºF is pretty warm so perhaps you only get 2x the WRI so less than 2 years. The point is that you are around the edge of what you can get away with for water replacement. Replacing every 6 months should not be necessary -- that's the timeframe for a real 350 gallon spa for 30 minutes of one person soaking every day and using the Dichlor-then-bleach method (Dichlor-only needs a water change in half that time so twice as frequently).

As for chlorine vs. bromine, there is nothing wrong with using chlorine at higher temperatures and many spa users with hot (104ºF) spas use it successfully, BUT the key is to use some Cyanuric Acid (CYA) in the water otherwise the chlorine is too strong. It sounds like you have been using chlorinating liquid or bleach without having any CYA in the water (either from adding pure CYA initially or by using any stabilized chlorine, Trichlor or Dichlor, products). The itchy skin and destroyed bathing suits are most likely from your high Free Chlorine (FC) levels with no CYA.

As for your chemical regimen, the only addition I'd make to what Ben listed would be to add some CYA to the water (he does mention this later in his suggestions). Probably using 20 ppm CYA is sufficient and you would then target 2-4 ppm FC as your normal FC range. This is somewhat higher than normal FC/CYA ratio in order to help oxidize bather waste faster and reduce the amount of measured CC, but you may need to use supplemental oxidation as well if you find that CC persists. For hot spas, the high temperatures break down the bather waste with chlorine fast enough, but I'm not as sure how 95ºF will do -- I think it will be OK. I know that 80ºF in an indoor pool doesn't do well without supplemental oxidation or UV in sunlight.

I wouldn't add 5000 ppm salt. There's too much risk for corrosion unless you are very familiar with your equipment and know that it will tolerate such levels. 50 ppm Borates is something many people find helpful for a shimmer to the water, but I'm not so sure it will have as noticeable effect on skin. The irritated skin came from the FC with no CYA and you'll be fixing that by orders of magnitude.