Jeans and T-shirt, jacket (hi-vis) with pockets.
They are comfortable and in a bubble canopy, heatstroke is more of a danger than fire and Jacket gets stowed once inside, with anything I need placed in an accessible place within the cockpit. With a 5 point harness, most pockets are pretty useless anyway.
In winter I use leather gloves.
In small GA civil cockpits, fire which gets to the point of burning the occupants is very very rare, and then if it happens and you aren't able to be rescued / are not on the ground, you are going to really struggle if cutting the fuel and electrics don't help. I suspect that the extra time that Nomex might bring isn't likely to make much of a difference.
The glass breaker things are designed for tempered glass (for which they are very effective). For the perspex screen in my plane they would just bounce off. Seat belt cutters are of use if the seatbelt is being held in tension, but there aren't pre-tensioners on aircraft belts. Also, my aircraft has a rotating clasp which will still release the belts when they are under tension so no need for the cutter.
A call on 121.1 or squawking 7700 is likely to be as effective as a PLB... I only bring one if I'm going to be over inaccessible terrain / water for a length of time.
I do always look at NOTAMs and weather (including local airport metar), do Auth Sheet and go through Tech log. I don't always do a weights and balance, because with me and the Bulldog it is impossible for me to go outside the limits (I will if I have a passenger or theoretically if I had a lot of luggage - hasn't happened yet). I only look at field length / performance if I'm not taking off / landing at an international airport which has many times the runway length that I need.