How can I determine the remaining hours of recording?

You can see the remaining hours of recording on the Create Project screen, and also on the Dashboard.

You can see the available hours of recording in the Console app on the New Project screen under SAVE PROJECT TO:

Recording_Time.ashx

You can also go to the Dashboard to see the available hours of recording under the middle pane on the left.

It is possible to increase or decrease the available recording time by adjusting the video bit rate slider. (Increasing the bit rate reduces the amount of available recording hours, and vice versa.)