Considering my first Mac purchase

Yes. There's no issue using non-Apple keyboards and mice on a Mac.

I use a Logitech Trackball and it works fine.

If the wireless combo uses a usb receiver, you can plug that into the Mac's ports.

If they use bluetooth directly, you can pair then to the Mac.

As you probably know, most Macs come with tiny SSDs (256GB) unless you pay ridiculous sums to upgrade.

An additional 750GB to bring the drive up to 1TB costs an eye-watering £400 but you can simply buy a USB-C NVMe and plug it in.

Good quality 1TB can be had from Amazon for around £70 and 2TB will set you back just over £100.