Make polyobject middle texture walls have alpha 0 upper? (train)

[rescue86k]

I'm using Zandronum as the base engine, in UDMF format. So a duke nukem train is possible through GZdoom (Mimic/tricks) with portals, but for the Zandronum, I did get the train working, its very basic, a polyobject with conveyor belt. The problem is it will have to go into the sewers due to the polyobject stretching to the ceiling.

 

1) Is it possible to apply a texture that its upper half is alpha (0) and able to shoot through it?  

2) Drawing a ceiling / and or floor to the poly object's "moving location"? 

3rd) Off topic question, how do I make the portal "things" work? Do they work in Zandronum? I read the acs code only works GZdoom? Portals be so much help if could use.

4th QUESTION) Off topic question, Where can I find an already made "close enough" model for Zandronum I can use that I can replace its texture to mimic a moving transportation rover for the top side of map? I think even something similar to a space ship or vehicle, cargo. I can replace /modify its texture. 

 

This is the prototype, its not fancy to look at[attached image]. It's the test zone outside the map.