don't bother with the Nairn for trout - as the only ones there seem to be sea trout ( I think because the in-river feeding is so poor...or so I have heard it say)
The Findhorn you wont really find trout fishing as its really a 'salmon river'. There are trout but you'd probably not want to pay for a salmon permit !
Like you say there are quite a few lochs down the whitebridge road - but ive only fished a couple of them. Knockie being one.
I like Loch Tarff and its got char in it too.
Loch Ruthven is good - but is boat fishing only
plently of lochs to have a go at