Welcome to the Strelets Forum. Please feel free to discuss any aspect of 1/72 scale plastic figures, not simply Strelets. If you have any questions about our products then we will answer them here.
Haythornthwaite's book is ECW - but I have no hesitation in reccommending Eduard Wagner's European Weapons and Warfare 1618-1648. It is available on Amazon - or it was a few months ago.
As for figures I tend to stick to plastic - simply because I prefer the proportions to metal figures. Show me a metal figure that is as finely moudled as an ACTA, a Revell or Zvezda and I would probably be interested. It's a bit of reverse snobbery on my part, I suppose, but I just prefer plastic figures.
As for sitting on a huge stock - well it's funny you should say that. I went looking for my figures and came up short. Looked everywhere, until a friend told me I had loaned him some cavalry, which he then returned. Sadly I don't have a massive reserve stock. I wish I did.