Hello Andy,
I think a few on here including myself would recommend a Bambi. I use the cheapest of the range, and it's a very nice compressor. Mr Paint by Ian recommended to me, and what a recommendation, it's been amazing.
http://www.airsupplies.co.uk/air-com...mpressors.html
The one your looking at look's like one of those cheap Chinese things but wrapped in a fancy case? I could be wrong though...
I don't think 0.5 is wide enough to spray liquid mask... Would you thought you need a spray gun of 1.3 ish - Then again I've never tried it as it's seems like hassle to clean the thing out after.