Sounds like the problem you're having with the stopping after one bar in record mode is because you're prepping in a 'bad' way

In song mode, in the playlist first make sure you have highlighted the portion of the track you wisdh to automate aspects of by double clicking and dragging on the timeline at the top

Then [important]make sure that you have an EMPTY pattern selected on the left hand side[/important] - press record and play and do the business - the reason it is stopping after a loop is because you have a pattern with sounds on selected, are therefore recording automation to that pattern (bad practise because if you do this you will inevitably lose track of your automation)

Basically keep patterns with automation and patterns with sequences completely seperate.