I have been trying to IPO a number of state corporation in the last couple days:
The 100B asset minimum is definitely correct in my experience, I have been adding cash to get just over that limit so I can IPO, and it works. Unfortunately if your corp has 75B in cash, you can't transfer more cash to it...so you can't just dump 90B cash on a corp to get it over the asset limit and IPO it.
P/E maximum 20 in my experience, but the limit could be a bit higher maybe.
I IPO'd a 45B value corporation. So if that is a factor, the floor lower than this.
The "why can't I IPO" messages on the corporation page are totally worthless, and should be mostly ignored.