I would love a few sneezes. I could tear my eyes out with the itching, if i swim in the evenings then my nose gets so full of mucus i have to prop myself into a seating position otherwise i "drown" in it. I spend about 24 hours sneezing and itching everywhere. When i used to swim 11 sessions a week as a kid i always had a "cold". Found out aged 22 i was allergic to chlorine. Those pools with the uv filtering are great!!
Moosey - i get the same, it could be either allergic rhinitus or sinusitus. I take flixonase spray (which you stick up your nose) which alleviates it (doesn't quite cure it with me though). The skin part - wash with e45 or similar and always moisturise.
I'll try swimming 400m with and without tumbles and let you know the difference - won't be able to report back til monday though so you may need to remind me.
Trunks - or lycra shorts - will improve your speed, for people who sink a lot it will also make them less negatively bouyant. tumble tunring isn't showing off and to be good in a race you have to practice in training.
Daz - tumbles, i reckon i take about 0.5-1 second per turn out of most swimmers (tri level) but my touch turns are also faster (26 years of practice and knowing how to be aero(aqua)dynamic) If you are not confident that you will come out of the turn in the right lane or pointing in the right direction then don't use them as you will end up slower (i have seen people end up in the wrong lane at loads of swimming galas where they are promptly disqualified) if you did it in a tri i don't know if that would also be the case.
Cougie - yes a wetsuit will help you float. If it is just your legs buy a pull bouy and try swiming with that.