One small thing I saw today while playing post-release beta 2.6.12:
I've got these neat buttons in the 'Firms' tab, which I can use to turn the sale-status true/false. I assume they're supposed to take two clicks (i.e. a double-click) to change their status (to prevent mis-clicks?). But, I don't think you're supposed to be able to put your Headquarters up for sale? After all, when you go to your Headquarters, there's no option in there to put it up for sale.
Before putting my Headquarters up for sale:

Afterwards:

Sure enough, some unscrupulous character has placed a 'for sale' sign in front of it:

Also, I didn't realise you were serious about that expansion pack stuff, and that you're really going to develop and release it (them?). After seeing some of the in-dev screenshots, my considered response is: TAKE MY HONEY, TAKE MY MONEY, TAKE IT ALL, * empties wallet and throws it at screen *.