How tall a ladder (A-frame ladder) do I need to paint a 16 foot ceiling? Will a 12 foot ladder do it, or should I get a 14 foot?

Hello, I have a driveway that comes down and wraps around the house. I'll estimate it at slightly under 45 degrees. I need to get up a ladder to install a bathroom vent on the second floor from that side. How do I place a ladder on my sloped driveway without it tipping over? Sounds like a math problem, but its not! Thanks for any useful advice.

The cages that surround very tall ladders, how exactly do they make the ladder safer? If you were to fall wouldn't you still just bounce down the cage, doesn't seem much better then having it open.

You can buy the ladders, and even have them custom made, but they cost close to 1,000. I know how to build an angled ladder. But I am building a loft bed (6 feet high), and I want to have an angled ladder that travels back and forth. I want it to be safe, and similar in design to the ones at the library, barnes & noble etc. What hardware would I need, and can I get it at Home depot or Loewes? I am open to interesting ideas.