How much time is usually spend at the hohensalzburg fortress? I arrive at the Salzburg airport at 10:10AM and have a lakes and mountains tour scheduled for 2PM, would I be able to visit the fortress in this time frame?
That seems tight if you need to get through immigration/customs, go to your lodging and drop off bags, grab lunch somewhere, etc. There are some exhibits and things at the fortress but it is mostly just walking around so you might be able to see some of it depending on how fast you move. You don't mention where you have to meet the tour group which could impact your time as well.
I'm flying in from Germany so I'm hoping that I will not have to go through customs. The tour bus leaves from the Mirabell Palace, and I was planning on renting a bike from the hostel I was staying at to get around the city. I am mostly just interested in walking around the fortress area to get views of the city and what not and would be willing to skip the tour if tight on time. How long does tour in the fortress normally take? Does the reduced price ticket still include the tour?
From the time you board the funicular at the bottom of the hill until you get back off again, you can easily see the fortress in well under 2 hours. The tour of the rooms that are open to the public takes about 30 - 40 mins. and you can walk around most of the fortress in 15 minutes or so. Taking in the views can take as long as you like - the views are great! There is also a restaurant up there if you want to stop in for a bite to save some time.
Even though it doesn't take too long you'll be cutting it very close.
You will go through passport control/immigration in Germany. You will go through customs in Salzburg, but this entails walking through a green door indicating that you have nothing to declare. You'll probably be out of the airport, checked in to your hotel, etc by noon if you are lucky and the flight is on time. I don't see how you can visit the fortress in this timeframe except looking at it from below.
If you're coming from Germany, you will not need to clear passport control in Salzburg as Austria is in the Schengen zone. If you're just looking for a nice walk with views, just take one of the footpaths from the Altstadt towards the fortress and walk across the Mönchsberg mountain. You will have great views of both Salzburg as well as the valley looking south towards Berchtesgaden. At the end of the walk, you will be at the Augustiner brewery.