More mindbending questions!
1) Say I cast a Shadow Genesis using Invisible Spell. What does the resulting demiplane look like?
2) My invisible demiplane has normal, fertile, invisible dirt. Say I then cast an invisible shadow TC to get 60 cubic feet of assorted seeds (grass, oak trees, shrubberies), which I then plant in my invisible dirt using an army of invisible unseen servants. Then I get a Druid, cast invisibility on him (hey, why not?) and have him hit the whole shebang with plant growth. Do invisible plants grow?
3) Say I then get into genetic experimentation and create a crossbreed between a pixie and a dwarf, let's call it a Dwixie, which is a naturally invisible stoneworking race. I then import a whole bunch of them onto my invisible demiplane and have them start mining invisible stone and metal, which they combine with invisible wood from question 2 and create invisible siege engines. Then I train my dwixies to create an invisible army outfit with invisible equipment, and go to conquer Spain.
When one of my invisible dwixie catapult crews fires an invisible stone from its invisible catapult, what happens? Do the catapult and/or the stone turn visible again? The invisibility of the wood and stone parts is separate from the invisibility of the dwixies (who have greater invis anyway) that are actually "making the attack."