Just recently my 07 HCH II started having issues with the alarm. Push the lock but tun twice it doesn't set the alarm and all doors lock but drivers side. My daughter noticed that the door would lock intermittently while driving. If I use the switch in the car it will work all lock but the drivers side. If all doors are locked and I manually lock the driver side it will lock all doors.

 

No idea. Remote quit working on my car, so I just use it w/o remote entry.

 

It would not hurt to lube the linkage. Since the drivers side door is the most frequently locked/ unlocked it may be a bit sticky. Combine that with a 9 year old electric motor and the door might not always lock as you are seeing now.