We used Rabbie Tours and you can chat directly with company from their website. When we did the tour, the Inverary Castle was closed, so we only walked up to it (about 15 min flat walk) and I don't think it opens again until April. Oban was our lunch break and there were plenty of restaurants to choose from, so you should have vegan options.

I went on the tour in November, when the castle was closed. The bus definitely stops there! It is at least an hour long stop, during which you can walk up to the castle, take pictures from outside and you will have enough time to grab a coffee or casually stroll around the lake too!

I believe it was closed as of early November. Our guide also told us that when the house is open they do not allow visitors to view much of it.

We left at 8:30 AM and got back to Glasgow around 6:00 PM. But Andrew (driver) mentioned it was entirely dependent upon traffic, which we didn't have a lot of.

When I went to this trip, there were in total 5 stops on the way with the possibility to use restrooms, the longest break between restrooms being around 2 hours.

I don't work for this company, but I took this tour at the beginning of August and it ran from 8:30am until approximately 7:30pm, so I don't think it would work for the timing of your day. There seem to be other tours available, and on Rabbie's website it says their Loch Lomond & Stirling Castle Shore Excursion from Greenock stats at 8am and returns to Glasgow around 4pm! I hope you find something fun to do!

We had very rainy weather, but had water resistant shoes and rain jackets with hoods, so were very comfortable the entire day. The terrain is not difficult, so hiking boots aren't needed for this tour.

Yes my experience agrees with above, we returned to St George Sq at around 19.00hrs. Note this was in early May, we had dry weather, good visibility and minimal traffic.

In the order of 4 hours comprising approx 2 hours in Oban and multiple short breaks at various attractive sights.

I'm afraid not, there is only one pick-up point and that's the starting point at Parish Hall, 266 George Street (next to City Chambers, George Square). This applies to all Rabbies Glasgow tours.