1 - You can use an adapter ( 1/4" to 1/8" ) in the line-in. That's what I do and it works great. Personally, my sound goes Guitar - effect pad - computer.

2 - When I do lessons I record audio on the computer and the video on ... well ... a video camera lol. The I sync up the audio later on. I've never tried to capture both the audio and video at the same time.