Regarding #6:
Many MMOs have auction houses that are "seller's choice". When you sell an item you pick:
Starting price AND/OR Buyout price
How long to keep it on the market (there is usually some maximum allowable value)
If you do a start price with no buyout, then it's a full auction. Highest bidder when the time runs out, wins.
If you do a buyout price with no starting price then it's a flat sale. First person to meet the price gets it.
If you do both then it's an auction but if someone meets the buyout, they get it immediately.
Pretty standard. If I recall correctly, EVE was a straight buyout market (I don't recall there being auctions) and POTBS had sort of a weird blind system, which was technically a buyout market but sort of worked like an auction.
You definitely can't go wrong emulating EVE's market, though.
Regarding #5:
It would be interesting if there was a simple API (something else EVE does, to an extent) which allows developers to create programs that query the database. Then we could more easily develop our own apps to do things like this. There would also be a potential for someone to create, say, Droid and iPhone apps for Strategus, rather than having to use the web interface.
Pretty sure we can do this anyway by just querying the web page for results but an API would probably save hassle and bandwidth all around.