I’ve not tried rectangle itself but by all means give it a go; I think snapping and tiling windows are brilliant (the multiple workspaces on osx fit nicely with this too). The mac I used to have was a little bit older and it seemed to support most screens (at various points I’d have used vga, dvi & hdmi) but it was a case of getting the right adapter for the thunderbolt port (eventually found one that had all of those in one). Just double check the options for the monitor you’re using and make sure they match up (a wee web search to double check the support might save you some trouble down the line as well).
If you wanted more peripherals on that some port then you might need a separately powered dock (price starts to add up here). Probably worth a bit of research into your own requirements/budget so a lot of looking before you leap, just in case.