Holy craaaap that's awesome! That absolutely blows me away...
How is he going to be based?
Question answered below 
About the edge highlights.
As someone who have built military tanks for the last 40 years i have observed that GW hobbiests are virtually the only ones that use the edge highlights, for me who as preiously stated that edge highlight looks very bad, sorry to say that, i suggest that you visit a military museum and take photos of what military vehicles actually look like especially especially overall appearence in regards to their natural paint coverage. A very good paint job deserves nothing less than accuracy, kill off the edge highlights.
I was going for quite a stylistic paint job like @Maidel mention! A bit like the one here, take a look:
http://www.warseer.com/forums/showthread.php?t=149051
I have to say I agree, I definitely could tone down the edge highlighting, on the lower edges of the vehicle in particular.
i thnk the demon prince looks really cool! the falcons head and the wings give it a really Egyptian look
i also rally like the blending you did on that one arm on the first page... looks superb!
got a question though, are there any other psykers know to use pyrokinetic powers ? like salamander librarians? and would it even be possible?
+sub and +rep
Thank you very much for the compliments and rep! I am not entirly sure if other psychers use their power to control fire etc, I'm sure you can find the answer to that question somewhere on the forums here or on lexicanum or a similar online 40k encyclopedia, sorry I can't be of more help!
Very good idea for the DP.
His hand looks a little large comparted to the rest of him; it might look better once he has both arms though.
Yeah I know exactly where you are coming from, I think it looks a bit better now though, check the pics below! My excuse is that he is a Daemon Prince, he has wings and claws, wouldn't be so surprising if one of his arms was slightly bigger than the other!
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Anyway, here we go! The DP is nearly finished! Just need to finish touching up some of the edges of the greenstuff. His crotch looks a little unnatural but he is going to have one of the loincloth things the thousand sons models have, it looks more normal from the back!
And a better look at the base! I am going to maybe add some old tattered books, scrolls and papers as well!