that looks catagorically the worst way to do all of those trails.
Descent into Fords of Avon is best from the aviemore side – The climb onto an lurg is largely ridable also – From fords of Avon through to The top of descent to derry lodge is a slog no matter which way 2km of push – The descent into derry lodge is fun also – well it was on friday night just past in the dark
The Lairig ghru is largely best avoided on a bike 8km push/carry Its a very good hill run through. – do the glen feshie route which has a 5k bog trott at this time of year due to the water table – from about 3k after the red house to about 1km after falls of eidart (i went through it on saturday) then some fun singletrack mixed with landrover track and back and forth till you get back to auchlean and hit the road – you can then flick onto some more singletrack round the back of loch an Eilein at the Gliding club and then go up to the fork with the Chalamain gap from the aviemore side if you really want to ride the best of the lairg ghru riding. –
Either way bottom line is – be prepared to push and take many spare tubes. one of our party got through 2 tubes and a while patch kit after splitting his tubeless tire at the bead on a water bar.