I can try and offer some answers to some of these questions to get you started. (There is a lot in MSFS that is “buried” deep within its features, for sure) I am sure others will be able to add better and more full answers as well.
For both of these I use the sim’s drone camera. If you set the movement speed of the drone cam to really slow it can simulate walking. There is a detailed guide on using the drone camera here on the forums
https://forums.flightsimulator.com/t/how-to-using-the-drone-cam-tips-tricks/128165
(Don’t forget to click the little triangles beside “important shortcuts” to expand the post)
There are probably quite a few youtube videos out there now as well about using the drone camera.
I use buttons on my joystick to activate exterior and drone camera views. I do use an xbox controller which makes operating the drone camera a lot easier.
I don’t think exactly what you are after is available. The closest may be when pressing Esc there is the option to Restart Flight. However, this literally does exactly that, restart the same flight as if you had pressed “Fly Now” from the world map.
I hope this helps a bit.