Interesting design choice, that makes it an entirely different game play. I expect people to be less likely to overbid by a tiny amount this way, but it levels the playing field for everyone: nobody can build on their previous bids.
Maybe, when your site has many active players, you can experiment by adding "accumulation games" to see which one is more appealing.

It was. Does that mean not showing the deposit was intentional? That can be confusing if someone bids a certain amount right after someone else bids a higher amount. I'd say both bets should show up.