Glad to see that you got round to doing one of these cant wait to see your work progress. Yes WIP's are fine btw, Just think of this as an online sketchbook, to post your work in at any stage. The community loves to see work as it comes together, and it is great to see how much time and effort people put into their work. Your Wip's will also help members to see your techniquies and learn , and also give them inspiration. And you get to show off your hard work so dont hold back
I love your sculpts, personally I would go for stylised, or some way of doing your own take on the concept art, rather than just copying it and trying to make it just like the painting, but thats just me. I believe that you have cameras if you just want to copy something, and when you have such powerful tools at your fingertips as Blender and the likes, then why just copy something that already exists, when you can do something that has never been seen before. I only ever copy something exactly when its the learning thats more important to me and its something fairly quick that is not worth doing my own idea for. Even in tutorials I usually design my own version of what the tutor does, so I not only learn something, but have a piece to call my own at the end.
Anyways , my only critique on the sculpts so far is that I think the fingers are way too long on the spacesuit model. I started reading at the bottom of the thread , so as I scrolled up I saw the suit, then the alien above and assumed the fingers were his at first.
Keep up the great work