Can I place live bids in an auction even if I have already submitted a maximum bid?

Of course, you can also place live bids. Simply click on the "Live Bidding" field and log in. When your lot is offered, you will notice that your concealed bid is active. You will be informed if you have placed a leading bid (up to your maximum bid, without needing to bid actively). If your maximum bid is outbid, you can increase your bid by live bidding.