Hello @brilliantlights!
Let me try to answer your questions 
Such effect with filtering it is jQuery plugin, like isotope (http://isotope.metafizzy.co) or mixitup (https://mixitup.kunkalabs.com). You can use it with Webflow, but it will require some custom code.
And yes, those pictures get opening in lightboxes, they just styled like a main page.
Hope it helps.
Cheers,
Anna