while interesting, the current market UI is not working as intended really and adding more to it would only make it worse. let's wait and see if they can get this UI figured out and working properly before making any other changes to it.
I don't see why all of this suggested could be coded client side of things so I don't see it breaking anything more.
I say go for it.
In order to help mitigate some of the potential mistakes in bidding/posting in the CH I was thinking that these three things might be of great benefit:
1) After each transaction, reset all quantities to 1 and amounts bid/asked to zero.
2) ADD a button to the posting pane "Last" which would automatically input the amount of your last post. Useful for posting multiple, like Enhancements.
3) ADD buttons in the bidding pane "Last", "High", "+1", "+10%", "+50%" and "Double" buttons. Hitting "Last" would duplicate the last bid posted, "High" would duplicate the highest of the last 5 bids. The incremental +1, 10, 50 and Double buttons would modify your present bid by that amount.
Keeping our rushed, tired, fat fingers off of the number keys would certainly save many people from a lot of mistakes related to manual number entry.