
Hello Samid!
We did a bit of the NCN7 a few weeks ago, very scenic, I'd recommend it. I'd agree with the suggestion of joining it from Callander. The section between Callander and Killin has a lot of non-tarmac car-free tracks, but mostly good surfaces.
If you want to read more opinions and look at lots of great photos, there is a recent thread
here (also including pictures etc for sections further north & south).
From Killin to Logierait (just south of Pitlochry) is almost entirely on quiet back roads, and mostly very easy, with a few "undulations" thrown in along Loch Tay, no long climbs, just lots of wee ones. I haven't been north of Logierait on the NCN7, but would very happily do the southern section again.
As for accommodation, there is a
bike-friendly hostel just a couple of km west of Callander (along NCN7 heading in the direction of Aberfoyle). We stopped there for a chat with the owner, it looks great (but we didn't stay).
Hoping to catch you in Edinburgh before or after your tour, the 18th is the date of the
annual Edinburgh-St Andrews ride - which quite a few CCers do every year, a great ride with an amazing cake stop

.
If you fancy joining us for the day and setting off on tour the next day (or go via St. Andrews), there is more
here, including a map and a few CC Ecosse members are mentioned in the write-up, see if you recognise anybody
T