Can't believe I haven't looked at this for such a long time!
Personally I think that the very small scale stuff casts best in metal, frankly it's runnier than any two part resin or plastic mix (in my experience that is, I had some epic resin Tau which were frankly a joke). The trouble is you need some serious starting investment with the big high pressure machine to make the casting disk mould and then there's the centrifugal spinner and melting pot - and metal. That said, most of these machines are pretty hard wearing and you'd get at least 200 casts from a mould (I know that some moulds have been running for 30 years!). If I had the dough, I'd do it in a heartbeat but that's probably because I'm a bit old fashioned and prefer metal to resin or plastic.
I think your beastie has a lot of promise, sure there are a couple of things not quite to your satisfaction but part of the freedom of sculpting is the ability to subtract and then add until it looks right. Also, if you haven't got one already, a digital micrometer is amazingly helpful (and very cheap) - like in drawing, accurate measuring is probably the most powerful tool (and if you get it a bit off, like me, it still looks ok).
Something that I found useful when starting to sculpt one piece miniatures, was looking through my collection of older figures from the 80s and 90s (as well as some of the simpler Rackham figures) since these were almost exclusively one piece metal casts. The range of poses from Dwarf Trollslayers to Eldar Harlequins cover pretty much every pose you would need. Lots of 15mm ranges also tend to be one piece casts (with the exception normally being alternative heads) and a quick look at pictures of ancients, wwII and beyond should provide plenty of references. There are common elements which recur in miniature sculpting because they work, you'll start to recognise it and it'll become instinctive so just enjoy the making!
I look forward to seeing your latest work.
