Space Exploration mod will place Menarite/Immersite nodes in asteroid belts and space but one can not place down the structure in space (also cant space any other Krastorio structures). Any chance to add support to place them on Space Scaffolding and Space platforms? (for that matter, liquid matter stuff would rock up there too)

Perhaps this makes sense. I am not good familiar with the SE mod, but I will talk to Linver about it. Perhaps we will add the ability to build more buildings from Krastorio on platforms in space. But I can't promise it, because the SE has its own analogue of matter and it is possible there is a sense to separate them.

I banned all Krastorio building from space that I'm not sure that fit well. Could u give me a list of Krastorio building that should be builded in space?

Honestly I'd be okay with all of them. But the miners are practically required given there isnt any other way to mine Menarite/Immersite. Your fusion and antimatter power generators along with the means of making antimatter would be a blessing as well.

Liquid matter facilities, oh yeah. Then rockets could be transporting barrels of liquid matter up. That would be so useful.

For sure any building that have smoke effect could not be in space. I think that good candidate could be antimatter reactor and miners, lab building already are placable in space