There are threads here about the LG Ultrafine 5K.Anyway, if anyone has any experience with it, I'd love to hear about it.
LG displays (the affordable ones anyway) seem to have a lot of bad reviews online. I don't know if that is because more people own LGs over say BenQ, or if LG just doesn't care to QC their lower cost displays as much as some other manufacturers.
So I am looking at BenQ and Dell monitors, though the latter appear to not play as well with Macs as LG and BenQ.
I am like you, pricing out a Mac Mini set up. I have decided to try the same Acasis box you referenced.
But for Time Machine: my current Time Machine HD (and it is the sole HD I still have) is running off of a FireWire (!) port. Does fine for my use, but the first Time Machine save has to save entire volumes so it can take overnight. The incremental backups are of course much, much smaller.
So I plan to go with a TM hanging off one of the regular USB ports on the Mini, probably through a USB hub. 5GB/s will be fine.