A few things... Yes, you are overanalyzing things, but don't feel bad, we all do it. It's part of being a forum member.
Also, it's interesting to see how many of us (myself included) jumped into a Pentax DSLR straight from a Panasonic FZ.
I've had the older Sigma 17-70 for a little over a year. The 70 end is a little slow. I'm looking at trading it for a Tamron 17-50 as you may have read in another thread.
For indoor portraits, the FA50/1.4 is great. It's a good portrait length, but I personally would prefer something a bit wider.
I'm a bit confused about your question of the 28mm of the Tamron being too wide? Too wide for what?