OK. I started from almost total ignorance

about the Mac-Mini and a 4K Monitor. And a budget of $3000 ± Thanks to your instructive replies, taking one idea here – another there – I’ve come to a decision that’s a bit farther than where I started. But I think it’s the right choice for now.
From Nick:
I would get the 2.7ghz 21" iMac ($1299)…upgrade the ram to 16gig (+$200)…then get the 4k display you were thinking of.
With a 27" iMac…you don't have to get the 16gig of ram right away. With the 27" iMac's you can upgrade the ram later. And the 27" display is super-awesome (lots of screen real estate)!
I'm just trying to help you get the most for your money.
From chscag:
The 21.5" iMac models are limited to a maximum of 16 GB of memory (as far as we know). The problem with finding out if they can take more memory is that the logic board has to be removed in order to update the modules.
All 27" model iMacs can take 32 GB.
From Exodist:
IMHO the 3.4Ghz 27" iMac with 8GB RAM and 1TB fusion option is the best value($2199). Also you can still upgrade the RAM in this unit later on. But you just have to get what you can afford.
[BTW, I clicked on the link to his photography site and found some valuable information there.]
From johnodd4:
A 4k display might work but might only display in 1080p
From harryb2448:
Remember with a 21.5" iMac you cannot user upgrade the memory and memory from Apple is not cheap.
So here it is:
iMac with Retina 5K display. Everything standard except 16GB 1600MHz DDR3 SDRAM , and AirPort Time Capsule - 3TB. This last I take from my friend (BS, Computer Science. BS, Biomedical Engineering Technology), who suggested: “If you're getting a 3GB primary drive, I suggest a backup drive (Time capsule) of the same or greater size - you ought to be able to back up a pretty full main drive.”
And with the iMac with Retina 5K, I can add more later if needed. That 27” screen is going to take getting used to. It’ll be a new world in here, and out there.
Just over my $3000 at $3,098.00. So, as Nick said: “All is good!”
Thanks very much to each of you for reaching out. It’s much appreciated. I expect I’ll be back here once it arrives and I get it set up. I’m sure to have more questions then.
- Bob