Where is the best place to fly into?

If most of your travel is in southern Colorado then flying into Colorado Springs is generally less busy than Denver and a bit closer. With a lot of flights connecting there it may not make a huge difference.

What other activities are good to do in Cañon City?

Cañon City is home to some excellent rafting on the Arkansas River and mountain biking as well. It's also near the Royal Gorge and not far from Colorado Springs and Pueblo.

When is the best time to climb in Cañon City?

Generally the Spring and Fall are ideal but really you can climb year round. Owing to the low altitude and favorable weather there are many winter days that are climbable. It can get pretty warm in summer so an early start is recommended.