In case anyone is interested...
My Amiga 2000 is running happily and I have started backing up my disks via null-modem cable. I'll work on getting the network card running this weekend.
I only just noticed that in WB it said I had 800KB free memory, which seemed a little low considering I have a 2MB A2052 card inside. I just thought perhaps it was disabled in some way. Looking at avail showed 512KB chip and 512KB fast... hmm very strange. In my sleep-deprived brain (its after 2am now) I thought that it was somehow only using 512KB of my 2MB card - forgetting of course that the 2000 has 512KB of onboard fast.
I took out the A2052 card and had a look at it, to see if there was any signs of damage or modification or missing chips etc. It does have two sets of jumper pins, but I can't find out what they're for. Anyway, the card looked fine and wasn't dusty. So I put it back in the Amiga and turned it on. The Amiga disk screen came up, so I put in WB and it started to load... it got half way and gave some error that I could either hit Retry or Cancel to. Retry did the same thing and Cancel ended up rebooting the machine.
It was at this point that the Amiga totally freaked, power light pulsing, and wouldn't load the disk screen (stayed white). I soft-reset and then hard-reset the machine and it totally refused to do anything. So I'm thinking that the A2052 card was partially working before and now it's fried! I took the card out, checked the zorro slot for dust etc, then reseated the card to make sure it was in properly. No dice. Amiga wouldn't boot up. I took the card out entirely and the Amiga booted up fine. Bugger - I guess the card really is dead...
On a whim I put the A2052 into the slot next to it, and turned on the machine... it booted up fine! Loaded WB and its now reporting something like 2.6MB free... avail shows 512KB chip and 2.5MB Fast (so 3MB total)

So faulty Zorro slot or something? Weird!