1) I don't know of any way to create a time based recording in Theatre View, whether a once off or subscription. I understand your desire to stay in Theatre View, or at least your wife's. But it is so easy to set up a time based recording using a keyboard in Standard View, isn't there any way your wife could learn to do that? A time based subscription could be set up for all your regular programs, with a reasonable amount of padding to allow for minor time shifts, and you would never have to worry about missing a regularly scheduled program when you go away for a period again (until the schedule changed).
2) You can just click OK on the program in the Guide, then select "Configure Recording", then change the pre and post padding times. A negative pre-padding time is the same as delaying the recording start, and of course a larger post padding time will delay the recording finish.
So if a program is scheduled to run from 7:30pm to 8:30pm, and there is a 10 minute pre-padding and a 15 minute post padding, then the program is delayed 30 minutes before it starts, just change the pre-padding to -20 and the post padding to 45. i.e. Subtract 30 minutes from the pre-padding and add 30 minutes to the post-padding. That will record the program with the same padding as originally planned.
Of course, because you aren't using a keyboard, that is a lot of button presses.
However, for all my programs that may well have a delayed start due to, for example, an earlier program running over time, I just put a much large post-padding time in the Recording Rule. But I have four tuners and don't record an awful lot, so don't have to worry about tuner availability.
3) Yaobing is the primary TV programmer, although others do work on TV functionality at times. I don't know whether he would appreciate prototype forms or not. But if you are a capable programmer, have you looked into what you could do with a stand alone application and MCWS? Perhaps a bit messy, but if you have very specific requirement, a custom solution can't be beat.
i.e. Press a remote button, your custom code pops up over Theatre View, and reads program data from the currently highlighted program, using MCWS. You make whatever changes you want to that data, in the way you want to make the changes, then when finished, send the changes back to MC using MCWS. Not simple, but very custom.