Sounds good, although I'm slightly worried that the auction house will replace the regular market. Even if you have to pay a fee, and the fluctuation of prices might make your sale obsolete, it's a lot easier to just dump your items on the auction house than it is to sell it using storefronts.
I'm a little undecided on this. At the moment corporations have to be taxed on whatever they sell anyhow so as a result they would still end up paying taxes + fees if they used the auction house. I'm considering an outright bar though for corporations to use it. Of course that doesn't stop someone attempting to steal and put items up there themselves but I think the odds of a corporation having a monopoly over the auction house is very low (I personally don't want it to happen).
Loving the idea however. Is sticking something on the auction house going to be as simple as clicking something in inventory? Would be MUCH greater if you literelly had to transport anything there, and then stick it in etc. Using vehicles with space. Would also provide criminal roleplay etc.
Economies can generally be pretty tricky. Like highlighted if people just get way too much money then everything becomes way too devalued. But on the other hand you don't want everything (some things you do though) silly expensive so those starting out will not have access to it for a long time. Money sinks are generally the best way to avoid this. Stuff that rich guys can spend money on without letting it accumulate too much and devaluing prices. The auction house will be set up in a designated building, so you have to actually go there to place listings (and most probably to collect wins). Not sure on robberies and the like, but could always RP it.