Running a longer distance definitely improves your shorter distance times. It wasn't until i started doing 10k runs that my 5k improved dramatically.
Use http://www.mapmyrun.com - I think that's what most people use.
Also look at getting yourself a Garmin forerunner watch. I have one and it's fantastic.
What earphones does any of you use whilst running?
I bought a set of Sennheiser omx 80 and I forever have to readjust the right ear phone... They are designed for sport and supposed to sit and that is it....
Do I just have odd shaped right ear ha