1).. the second remote should not have been taken. In single mode with shared view enabled, both remotes control all functions of the receiver.
2) In single mode there really is no difference between tuner 1 or tuner 2, and you can stop the recording either by viewing it or selecting it and hitting the option to stop recording.
3) If you are viewing the channel but not the recording you can get the messages that were mentioned. Find the recording in the schedule and make sure you select it first in that case.