Help understanding some world editor quirks

[Banhammer]

I remember i messed around with the world editor in the past, but that was long ago.
Currently i'm trying to figure out how some of the basics work. To do that i've taken upon myself to duplicate all races and create custom variants of everything related to them.

So as you'd imagine a custom building would have to provide the custom units, which would use custom abilities, which would be enabled by custom upgrades whose techtree would have to account for the custom buildings so on, so on.
Going through this process had me run across a few things, i'm sure there will be more, but i already want to mentions the ones so far:

1. Sacrificial Pit - i thought this would be similar to morphs or a unit replacement sort of principle, but no, neither the acolyte's or the building's ability have any fields to designate the unit used or generated. I suppose the used unit is determined by who has the ability? likewise the generated unit will always be a shade? is it hard coded? as it stands i'll probably have to come up with a trigger to use a custom shade unit.

2. Siege Engine Barrage - setting it up was straightforward except when you go and test it ingame the building will allow to train both the non-upgraded and the upgraded versions from the get go.
to have it work as the regular version had to use a trigger
"Player - Make Siege Engine* (Barrage) Unavailable for training/construction by (Picked player)"

3. I tried repurposing the Divine armor type, and in the game interface menu there are 2 icons for it, one for the upgrades version and one for the standard version, but it seems one of those fields is not used, no matter how i set it up, one icon is used for both the upgrades and the standard version in game.

4. Limit one hero per type - the initialization trigger seems to have this bit included, likewise in the gameplay constants it seems i'm able to designate any custom heroes as hero units so the game would recognize them as such, but when testing ingame it's not limited to one, i can train more than one of that hero type. Don't know how to deal with this.

But yeah, that's a few i came across, if any of you have some suggestions as to how to circumvent some things or have your own things you had issues with, expecting it to work one way but turning out to not be like that, do tell.