Hudson:
Q1. It is the most common method to fly manually and A/T off. It keeps you in the loop more - on top of it etc - and stops the thrust/pitch couple problem, which really is a handfull. What is important is to know what the power setting should be for the approach conditions ie. weight and w/v speed increment, set it when on speed and you'll probably find, unless in very gusty conditions, that the speed will bounce around the datum and need very little adjustment.
I suspect the additive for manual flying is the mis-trust (tut tut!) of the pilot scanning the speed and not being as accurate as the A/T????? or even forgetting it completely and ending up very slow.
Q2. This really relates to a full autoland condition. The IDLE feature of the A/T will take care of this. I still use the +5 if making a CAT 1 to man land in full automatic mode.
Q3. See Q1. about setting datum thrust. As for landing fast and long with a large wind additive; I would hope most of the component would be headwind and thus a low ground speed.
Q4. Not easy to put a number on it as it depends what it feels like on the day, but if you had to start somewhere, a very slight thrust reduction at 200' is perhaps better than a large one at 100'.
Q5. Not sure about this as we've not been allowed to try it. It works on B757/767. As in many tech' questions these days I suspect the maintenance, rather than pilot, manual will tell you.
dvt. I'm not sure about the use of V/S in a G/A. I suspect this would be non-standard. TOGA will give you only 2000'ROC anyway. Hardly pocket rocket stuff.
One question I've had, but no answer:
You can fly an autoland with manual throttle (A/T u/s) and thus have to add the full W/V additive upto 20kts. The autoflare reduces the effective LDA. (i.e. it shortens the RWY) Autoland distances are compensated for +5kts (I assume). What is the effect of flaring with +20 or should the speed be bled to +5 by 50" as if the A/T was in command? If not, the a/c might float and the rwy becomes even shorter, so what would the required autoland distance be?