I guess I'm a little confused about the current models. a 13 inch MB Pro looks like it is around the same price as a retina macbook if I am looking correctly. What am I missing?
You're not missing much - in terms of spec you get a lot more with the 13" retina Macbook Pro than you do with the Macbook.
With the Macbook you are paying for lightness above all other priorities.
I'd suggest trying both out in the Apple store, figure out how much the less weight of the 12" MB is worth to you vs. the lack of ports and make your own mind up.
The CPU in the Pro machine is significantly stronger, and whilst it does have a fan, the 2015 machines run with the fan OFF the vast majority of the time so they are silent like the retina macbook unless pushed.
I did the same comparison a few months ago, and for the same RAM and storage the Pro was virtually the same price where I am ($100-$150 difference - not comparing base spec to base, but like for like with 512 GB storage). For a way stronger CPU and more ports. It's "light enough" for me, YMMV.
edit:
as to quad cores in a 13" box.... no thanks. The dual core is faster clocked, and it's not just heat, but the quad cores start at 45 watts or so rather than 28. You'll be giving up a fair bit of battery life, running fans harder and more often and throttling more often anyway.
I suspect performance would't be heaps better due to the throttling, the machine would be noisier and hotter. If you want quad core, buy a 15".
Apple (or others) COULD do a quad core 13" machine, but
intel pushes the dual cores at that form factor as the best trade-off for good reasons.