1) I'm not sure if this exists in the same way it does for JPEGs. Most programs will just add a metadata flag of "orientation" to the image and change it, instead of changing the actual photo. Video players I don't believe have this concept, so the video would need to be reencoded.

2) I believe http://www.irfanview.com Irfanview has a pretty good batch process. I had this on every Windows machine I used prior to my Mac switch.

3) Looks like Irfanview can help there too: http://www.makeuseof.com/tag/how-to-take-a-screenshot-batch-process-images-irfanview/