Hi Davy, All good advice given, but I wouldn't over-fret about doing a spot-on job on windows where you have to use a pole. Most sensible customers appreciate that unless it's "hands-on" the result won't be 100%.
If you're going to use the tapping method make sure your applicator isn't over wet as the "tap" will spray the glass you've just bladed.
To detail the fixi clamp is good and the order to detail is: 1st sides, 2nd top and 3rd bottom.
Don't worry about putting your ladders onto plastic gutters as they always have loads of give (I've been doing it for years without breaking one...just be a bit careful as metal on plastic has side-slip potential).
Lastly (although I'm sure you've already discovered this) have as little ladder above the gutter as possible...one rung is ideal, any more than 2 gets in the bloody way
Good luck Guv