Excellent advice sir. I agree with everything you stated about Oppo. I'm currently trying to help out my friends daughter who has only played outside and all-around. Now she just started college and asked to also hit right-side. She lines up 2' - 3' outside the side line with a strong angle to the net on the right side (she is right handed) just like she does when hitting outside. I have told her just what you said for Oppo. Straighter approach to the net. Start near to the outside line or inside and be able to hit the ball down the line, middle or cross. Thanks for your explanation and video.
Just a comment on the serve receive part - I am an opposite in a Youth League in Japan, and Im utilised for serve receive, but my general responsibility is covering for short balls/net ins. From my experience, opposites are the most well rounded players of the team, a good serve, block, hit and recieve.
Watch as much footage of Steve Timmons' playing indoor vball as you can. He's one of the top 5 if not top volleyball opposite in history. He could hit back quicks as well as any middle and basically pioneered the back row attack. If an O can learn how to hit a back quick and then run double quicks on offense, that team can manipulate the block as it sees fit.
Not necessarily, in general, outside hitters are expected to do serve receive while opposites are put deep behind other players, meaning, for the most part, they don't have to receive. Opposites are also often the second setter if the main setter can't get to the ball or got the first touch. But outsides and opposites are definitely the most similar positions.