In answer to your questions:
1. Engineer passed the car without heater, only electric demister (Cyplas suction-cup type - absolutely useless :-/ ) I only have single-speed wipers, according to NSW guidelines they're OK as long as they do 45 sweep/minute or better. Rules might vary in your state.
2. See the thread from Carla about her wipers for info on 2-speed units. Others might be able to suggest a heater, 'cos my experience with them is limited
3. I replaced virtually the whole floor, although it has both the remnants of the old x-member and the 'wings' from the HK floor now.
4. There's definitely advantages in getting a long motor with an auto already attached, since you can be sure you have all the bits and pieces like vacuum kick-down and so on you need. Which reminds me, the p-glide has a manual kickdown, via a rod from the carby to the selector on the LHS of the tranny. Make sure you get this if you opt for the glide.
cheers
RET