In answer to your first question, press the print screen button located aboe the insert button. Then go into a program such as paint and use the edit menu to paste your image in there. You can use any image program that will allow you to paste in images, crop to your liking and print it or save it or whatever.
In answer to you second question you can use the guides at Doom9 to use the necessary software for your subtitles. Just click on guides -> subtitles -> and under subtitle guides VOB -> text based subtitles using OCR.