hofmeister,
Undergrad chemistry student and homebrewer here. Some thoughts on your questions:
1) BRITA FILTERS. Yes, Brita filters do indeed remove hardness from your tap water. I base this on a few hours of research online in which I evaluated several independent tests which were posted online. Here are a few:
Missouri TV Station KFVS had an independent water lab analyze Brita filters:
http://www.kfvs12.com/story/307273/brita-water-filtering-pitchers
Undergrad chem lab report tests Brita filters. Interesting because it shows faucet-attached model significantly better at hardness removal than pitcher-type.
http://bit.ly/15Wescd
Science Fair project tests Brita filters. Use of TDS meter involved.
http://www.usc.edu/CSSF/History/2006/Projects/J0509.pdf
Also, pistolsatdawn’s post above with the quote from Brita’s website saying their filters do remove hardness from tap water.
Also also, the chair of my department assured me that a few years back they tested Brita filter water in the lab and he was surprised at how much of the hardness minerals it removed. Hopelessly anecdotal from your POV, but still.
2) Softening your water for homebrewing: DON’T DO IT. A defense of this blanket statement would involve a very complicated discussion of the various technologies employed by commercial in-home water softener units. doubtless there is some homebrewer out there who thinks his water softener homebrew is the bomb and will say I’m wrong, but I can virtually guarantee you that if such a person were to chime in, they would lack the technical background to be able to determine if your setup is same as his setup. (also keep in mind that you might think his hb was total dreck if you tasted it, so…
3) Your location. Consulting a water hardness map of the US (link below), I can see that upstate NY has a wide variation in water hardnesses. Looks like if you live ~50 miles to the S or E of Lake Ontario, your water will be hard to very hard respectively, and elsewhere soft. If you have soft water, then I say your water, esp after being Brita'd, should be just fine for a decent pilsener. If you have found your pilsener brew unacceptable, then I would determine which of your local big chain grocery stores have a water machine that you can buy water from. These machines are always reverse osmosis, and should dispense very soft water (<10 ppm of calcium) which should be excellent for your pilsener.
Hope this helps!
Water hardness map of US:
http://www.h2odistributors.com/water-hardness.asp