custom monitor cage question.

[Iceman]

hey yo,a few days before i get my new monitor(lizard)i will be going to reno depot,or home depot,and getting some supplys to build a enclosure....now i've seen hetforhumans design,its amazing,it looks like it would be really good for a monitor..
it will be either a nile,peach throat,savannah,or water,im not sure..i have a huge bedroom compared to all the other rooms in the house,so i decided instead of using tanks,im gonna make enclosure..or maybe a multi level one,and the 2 upper cages will be for my pythons,anyway..
i think i need a few questions answerd before i do this..

1:what is the best way to make the front doors?and maybe the easyest,like sliding glass,door opening down,up ext.

2:do you guys nail the wood together,or use screws?
if so whats a good kind of nail/screw(like what size and kind)

3:what is the exact best thing to use to seal the corner cracks in the cage?i dont want to use something that will be toxic to the animal..

thats pretty much it..can i also get some tips from good builders,like what kind of wood is the best,and all that
i was gonna use melemene,im not sure...

let me know