how much RAM does it have, graphics accelerator? Where does the mouse plug in?
You can see the specs here: http://www.microsoftstore.com/store/msusa/en_US/pdp/Surface-Pro-3-i3-64/productID.300190600?WT.mc_id=SurfaceBG=Surface-Pro-3-i3-64
But either 4GB or 8GB RAM.
you can compare it to MacBook air here (not exactly unbiased but good enough).: http://www.digitaltrends.com/computing/surface-pro-3-vs-13-inch-macbook-pro-retina-specs-features-prices-compared/#!PIkC6
It looks like it has one generation older GPU vs the MacBook Air. Will that matter? Depends on what you want to do with it.
Mouse can plug into the USB slot.