There are two questions here really Dave. First is about equipment, the second is about process.
I'd recommend the Silver Bullet 13" model, but it's outside your budget at £654.99. I really don't remember anything about the other models, save that I spent about 6 weeks researching in serious detail what was possible and what wasn't. Just reviewing a few videos quickly, the cameo has only 2 this light plastic rollers which keep the media in place while the platen moves back and forward. Mine has 4 large rubber ones which will grab smaller pieces of plastic. I have a feeling if you put plastic or card onto the platen that's not slathered with Spray Mount, the media might slip.
Now I'm looking at the RMweb thread in some detail, I'd be concerned that the corners are rounding on windows and so on. Mine can correct for what's known as blade offset and overcut. Either there is no option with that machine/software or he doesn't know how to tweak it to the best setting. If you see photos on any of those threads, zoom all the way in, much of the finesse promised isn't actually produced.
Inkscape and Corel are fine to have to actually drive the cutter, but you'll need some type of vector software to produce the drawing (AutoCAD etc.) which then has to be exported as .pdf (which retains the vector data, rather than converting it to raster) and then you need to import it to the cutting software.
If you produce your artwork like below, you will have to produce outlines on top, to tell the cutting blade where to cut it. When you print off the piece of artwork to be cut, you'll have to place it into the platen, then tell the cutter where the registration marks are so it knows where your design is in relation to the data on screen. This calibration has to take place for every sheet of artwork, and is a PIA. I do all my cutting by hand, still.
Anyway, read as much as you can on the likes of Amazon, RMweb, about all the cutters, get it to a shortlist and then come back here.
http://die-cutting-machines-review.toptenreviews.com/silhouette-cameo-review.html
A quick google tells me the Cricut is a bug ridden piece of rubbish. Tri-ang level. Never heard of Zing.
TL;DR - If you can produce the artwork of brick buildings, print it and cut it by hand.
R.