The major benefit of using a Mac is that you will find more/better video editing tools, which translates to more users, which translates to more tutorials on the web. You can search for all kinds of things like "how to (x) in Final Cut" and likely find 10 different tutorials.
The resolution of your monitor doesn't matter (to a point). In video editing you're always working with the actual video in a relatively small window (unless you have a dedicated full-scale preview monitor). Editing and such at full-res just slows things down, so a 1080p monitor is perfectly fine for editing 4K video. However, given how few monitors support 4k video, I'm not sure you *really* want to be doing 4K exports. It might be nice to capture in 4K so that you have more ability to pan/zoom in the image, especially if you're applying a stabilizing filter in post.
My current monitor is an LG ultra-wide (21:9) which I've found works very good for editing, lots of room to layout all the editing windows, controls, etc. It's not 4K though, it's 3440x1480.