Ok, see my reply to your post on Windsor and Newton Oils/Cotman in the Armour section for some answers.
Now, as to how to get rid of the 'painted' look and the shine. Once you have finished painting your figures, and they have dried for a few days, airbrush them with a coat of Matt varnish. Although it is not available to me, I believe testors makes a product called 'dull coat' This will stop the figures looking shiny and painted. I use Humbrol matt enamel varnish, but you may not have access to this brand.
A little more about Acrylics vs Enamels:
Acrylics can be found in tubes, and are similar in consistency to the Windsor Newton Oils that you have. However...The Acrylics refered to by modelers are thin paints, like the testors enamles you are using at present. They are applied in the same way, although they dry faster. The main difference is that Enamels are 'oil' based, and acrylics are 'water' based, although one usually uses rubbing achohol (Isopropyl Alchohol) as a solvent.
The type of paint that is contained in tubes is desigend to be applied thickly, in the same fashion that an artist would apply oils when painting a picture, the type of Acrylics you are after are the modeling type, and are made by (amongst others) Tamiya, Gunze, Model Master. Just because Acrylics are loosely 'water based' does not mean they are the same thing as 'water colours'. Acrylics are chemically complex paints that are a fairly recent invention (around the 60s I believe) and are perhaps more accurately refered to as 'Alcohol based'.
Paints like Cotman water colours are designed for use on absorbent materials such as the heavy paper used by artists for water colour painting, and are usually applied as a wash. They are much simpler paints, being basically a pigment suspended in a water based gum binder.
I hope this is of help. I have seen a discussion in the 'Plane talkin' forum on www.hyperscale.com about the chemical make up of Acrylic pints, but it was a few weeks ago, and I can't find it now, perhaps if you search through this site (another great forum for modeling) you might learn something.