20p means 20mm positive off set, i wont go into it, as there is a good diagram around in the wiki i think, that can explian it.

you also need to consider what tyres you wont run before you even think of rims

14x6 +8 offset is a neat fit on the rear (with 175/60 or 185/60 tires and standed rear gaurds), the same rim on the front will be close flush with the outside of gaurd.

i now have 14x7 0 offset with 185/60/14 brigestone re001's and the they stick out 50mm from the body line on the front and the rear they stick out 15-20mm..

in 14'' tyres you can get (aus):

165/65 - nice dia, but crap tread and getting rare
175/60 - nice dia, some ok brands and tread, but getting rare
175/65 - cheap, crap dia, bigger than a 185/60...
185/60 - ok dia, good brands and treads, personaly i love my re001's!!