Well as you are in macrmours I assume you fancy a Mac over any other make of PC, I would go for the retina MacBook Pro 13 inch, for the best compromise on portability, battery life, ports and performance.
I would also reccomend you wait for the next update if you can, it should be out sometime in fall.
As for software try out photos and see what you think it's very simple and has very few tools but it is included with your Mac. Then maybe pixelmator for a cheap simple but fairly useful editing program at $30 it's a bargain.
After that you'll have to research more professional options based on what you want to spend and how complicated you want it to get.