Two elderly people visiting Badalin Great Wall

We are 69 and 68 years old. My wife has problems climbing/negotiating steep steps or inclines. We will be in Beijing bteween 6th and 12th Sept 2013. We will be happy to use the cable car both ways. My questiona are
1. Using the cable cars how steep/slippery will still be the climb for us
2. Can we buy both entrance and cable car tickets at the same window
3. 2 hours generally allowed by the the tour companies...is this time enough for the Wall
4. Any other tips/precautions which we need to know.....this will be deeply appreciated