Nike + app and endo mondo apps are good, plus theres a 99quid gps watch in this months runners world mag - can't remember who makes it though, sorry! I was 2 years in before I bought a gps, started off using mapmyrun and a casio digi watch with stopwatch. There's a lot to be said for training as to how you feel too, rather than to a pace. Enter some races too: I ran 5k and 10k foot races, and bike time trials before entering triathlons. Are you a member of a club?
Giro Monza for me but I have a huge head - 8 3/4 hat size! All the other brands gave me a splitting headache and a big dent in my forehead, apart from a Laser MTB helmet I used to own, but I had to get XL so it was enormous and stuck out at the sides - I looked like a mushroom.
Agreed - start with a pool based sprint. If its local go and swim in that pool and have a ride round the course too. In training, practise your transitions - i do this by short fast bike/run/bike /run sessions (eg 10mins bike, 1km run, 10mins bike, 1 km run etc) - gets you used to getting your bike gear off and your run stuff on in a hurry while out of breath! Clubs can often organise swim/bike brick sessions too - great for practising swim to bike transition, which is a tricky one unless you know the pool owners/organisers. Enjoy and good luck!