I'm relatively new to the digital game, but I think I can help a little.
The specs of any camera or lens should be available on the manufacturer's website. Good camera dealers also include full specs in their web descriptions. I'm not familiar with the European photo market, but two good American sites are:
www.adorama.com
www.bhphoto.com
The digital camera market at the moment is enormous, with new products appearing every month - and the prices dropping constantly. I have the impression that most of the cameras being sold today are actually pretty good. The safest course of action, though, is to stick with one of the big, well-established manufacturers: Canon, Nikon, Konica-Minolta, Olympus, or Pentax. All of them have been making fine cameras for decades. Sony, Casio, and Panasonic, which got into the photo game early in the digital era, also have good reputations.
For taking closeup photos of models you need a camera that has either interchangable lenses or "macro capability." The specification that needs to concern you is the "minimum focal distance." For the sort of work you're talking about, you need to focus three or four inches from the subject.
To take decent model photos you probably need at least four megapixels. Several of the magazines say they'll accept three or above. You probably can get by with three - but only if you refrain from extensive cropping of your pictures.
Many of today's "compact digital" cameras have built-in macro capability. They also have tiny lenses, which are miracles of precision manufacturing but, according to the experts, just don't have the ability to pick up detail like bigger, more traditional lenses do. I don't speak to that point from personal experience, but I've heard and read it several times from people who know what they're talking about.
When I was shopping for a digital camera I decided fairly quickly that I didn't want one of those little "compact digicams." I saved up my pennies, watched the reviews in the magazines, and eventually bought a 6.1-megapixel "digital SLR" - that is, digital single-lens reflex. A digital SLR looks more-or-less like a traditional film camera. Lots of different lenses - fixed-focus, zoom, telephoto, wide-angle, macro, fisheye, etc.- can be plugged into it. I bought a Pentax *ist DS, mainly because I've been a Pentax man for decades and already had a couple of Pentax lenses that I'd been using with my film camera. I've had the new digital camera for about six months, and so far I'm delighted with it in every respect.
I'll make one other observation that may amount to heresy, but I think it's appropriate here. If you're primarily interested in model photography, and if price is a major issue (as it is for most of us), it just may be that a digital camera isn't your best option.
This is a great time to buy a film camera. The film manufacturers are still offering excellent products, and undoubtedly will continue to do so for some time. (The owner of the camera store where I shop is convinced that film will still be widely available for the rest of our lifetime.) High-quality slide or print film still provides greater resolution than any affordable digital camera does. (I've read estimates that it would take a digital camera of at least 18 megapixels to match the resolution of Fuji Velvia 100 slide film.) And some of the magazines (including FSM, if I'm not mistaken) still say they prefer photo submissions in the form of prints or slides made from film. Film processors (including drug stores and places like Wal-Mart) have machines that "digitally transfer" film images to CDs; you can get a 36-exposure roll of film developed and put onto a disk for about $5.00. Once it's on the disk, you can e-mail it, manipulate it with image-enhancing software (such as PhotoShop or PhotoShop Elements), and do everything else with it that can be done with digital photographs.
These photos were taken with a Pentax ZX-30 film SLR, on Fuji Reala 100 film, then digitized onto CD:
http://gallery.drydockmodels.com/hancock
http://gallery.drydockmodels.com/phantom
The best news about film cameras is that they currently offer a combination of high quality and low price that's never been seen before. My Pentax digital SLR body (minus lens) has a street price of about $800. You can buy a brand new Konica-Minolta Maxxum 50D film SLR body, complete with auto-focus, automatic exposure, built-in flash, and lots of other features, for less than $100. You'll also need to buy a lens for it, and for closeup model photos you'll need a set of closeup filters or extension tubes. But you should be able to get out of the camera store for less than $200. And if your community has a good camera store that sells second-hand equipment, you probably can pick up an outstanding bargain on a used film camera. Good photographers, who've taken good care of their equipment, are trading in film gear for digital all over the place, and the used camera dealers are unloading it for wonderful prices.
The "digital revolution" is seducing photography enthusiasts all over the world. (I withstood it for several years, but it eventually hooked me too.) It has a great deal to recommend it. But for the particular purpose of model photography, film offers a fine combination of quality and low cost.
Hope that helps a little. Good luck.