Just to add aj and Martin are both very knowledgeable in this area. I urge you to follow their instructions. If you want it very easy just add a bit of cacl and gypsum (sticky in brewscience). If you want to understand more you need to read more in bru'n water's site to learn more. Also the...
Wait a couple of weeks. Then pull off a pint or two of trub. You will have much clearer beer after that. You could also use gelatin to speed up the process. In the future try to get less trub when racking to the keg.
Here is a cheap option that I have been using on my MM 3 roller for about 3 years. They are all over ebay. Can usually get them for about $35. They are a touch slow but mine works great...
I know that these are not your numbers but that is a very low amount of gypsum(and salts in general) for an IPA. My calculator shows 80 ppm of sulfate.
My brew area is in my attached garage. It is insulated but not heated/cooled. I use vittle vaults for my base grains. For specialty grains that sometimes will be around for a while, I vacuum seal and store in a fridge.
I actually agree with Bishop that it is a lot of work for very little benefit. The amount left in the chiller and hoses should be relatively small. However, I think you can get this to work if you want. I number of people use air compressors to aerate so if I were to go through the trouble I...
I have never understood why the need to have the bag be all the way at the bottom. I doubt if it makes any difference. The only issue I have ever had when dry hopping in the keg is the bag somehow clogged the dip tube.
He does no sparge. He is asking about recirculating during the mash. I use a stainless bulb on a silicone tube to keep the tube just under the liquid level. I am not biab and I do this for the sparge also when I don't want to upset the grain bed. In your case I would just have the return under...