I think Insch opened in the early 00s, not long after Tullos. i can't even recall where Inverurie depot was. Alford closed about the decade ago with all services moving to Insch. At the time services in Aberdeenshire were getting lots of funding through different partnerships, so the PVR for the Inverurie area would've drastically increased (hence why Insch is so "overbuilt").
Buses get from Alford to Insch via the Service 422. -
https://bustimes.org/services/422-insch-alford-or-whitehouse
Part of the land at Banchory was fenced off for taxation purposes with only the area between the entrance and the front of the garage still used for parking, however part of the is still owned by Stagecoach and was in use up until last August with a allocation of 1 coach and 2 Solos. However currently these are just being worked out of Stonehaven and Aberdeen instead.
Both Banchory and Alford are visible on Google Streetview back when they were still in more active use.
Alford -
https://www.google.com/maps/@57.233...4!1svSysxh-haU1RlxqXMjSQsw!2e0!7i13312!8i6656
Banchory -
https://www.google.com/maps/@57.047...4!1sHWS4gzW0Jw02_PMDWo7sAg!2e0!7i13312!8i6656
Currently 3-4 Aberdeen based buses are out stationed in a yard just south of Fyvie for the 290/291, until around a year ago they used a Farm to the west of a village, however as the vehicle allocation has increased they've moved again.
Current Fyvie outstation -
https://www.google.com/maps/@57.420...4!1sM-7jRR8zu_SgS6-neLtcUQ!2e0!7i13312!8i6656
Former Fyvie Outstation -
https://www.google.com/maps/dir/57....206,-2.3648324,422m/data=!3m1!1e3!4m2!4m1!3e0
Lastly Macduff outstation is another that closed a few years ago, although in reality it was just additional parking for the depot that was down the road. Stagecoach now park 3 coaches in the carpark to the south west of Annies Cakery on Station Brae.
Former Macduff "overspill" yard -
https://www.google.com/maps/@57.668...4!1ssCxL2iMksimM_QSHrVh2yQ!2e0!7i13312!8i6656
On paper Fraserburgh and Ballater despite being proper sites with refuel/wash facilities etc are only regarded as outstations, The Ballater fleet being Aberdeen vehicles while Fraserburgh is Peterhead vehicles. The Bluebird opco is split in to 3 separate divisions (Aberdeenshire, Buchan and Moray) with each having their own controllers, supervisors and engineering managers, as such it's very common for vehicles to rotate between depots within each of those areas. Currently around 10-15 Aberdeen vehicles are being docked overnight at Peterhead for maintenance purposes while the Buchan Engineering manager has been helping out at Aberdeenshire (this is part of the reason why reliability has been improving).