Nah, don't worry about spoilers
Episode III is the cable that mates, at one end, with the end of Episode II, and at the other has to mate with Episode IV from 30 years ago. I can construct the general plot through simple interpolation between the interfaces. I had no qualms about reading your post, and thanks for pointing out things to watch for. I'd heard about Lucas's cameo, but wouldn't have known where to look for him. I'll probably go see it next week, during the day, to try and avoid the lines.