It is most definitely a great time to buy any new Mac laptop. Even if they do release a Retina 13'' soon, it will be a more expensive option than the current model. And as others said, if it were to be released by year's end, there is nothing Apple could really do to "upgrade" it. Apple is very consistent and it's likely, assuming they do make a 13'' Retina, they would keep the exact design of the current Retina and just shrink it. Port wise, the two are similar (15'' Retina and current 13'' Pro). The only difference would be the specs, but you'd probably get something you'd expect to see, spec-wise, from a 13'' laptop. I'd be surprised to see a quad core 13'' Retina by years end.
As for Pro vs. Air, I have to agree with several others that it seems like the Air would be a good fit for you. I think most people would enjoy the lighter, thinner form factor because it really is night and day compared to your average laptop. However, some people will always prefer a sense of heft in their machines. For those people, I can't really see myself recommending an Air unless I think they could change their mind. Based on your comments, it seems you might be someone who prefers heft, but if you could go try both models out and pick which one you like the most I'd think that'd be your best option. Both are good quality machines and I think you'll enjoy your choice either way. Go buy one today it's the best possible time to buy a Mac.
