There were about 3,000 people in the Spark Arena at each one, and when we left, there was a huge lightsabre shining in the sky, mounted on a crane which was invisible in the dark: very effective.
Lightsabres: yes, they were indeed allowed and you could see them waving in the audience during fight scenes.
Costumes: I saw several Jedi, a Stormtrooper who must have been sweltering in the humidity, several Leias, and a couple of Lukes. No Hans as far as I noticed: pity.
The Mos Eisley Cantina scene: we were looking forward to the orchestra doing the jazz, but they didn't. We and the people in the row in front sadly discussed this in the interval and thought that maybe John Williams hadn't written it, but that's not the case. It's now my theory that because it's part of the film itself rather than the score, it couldn't be removed so that the orchestra could play it.
[Edit] Playing elsewhere? Maybe there's a Star Wars concert near you! Have a look here, filtering for your country and Star Wars. It's very much worth going to one if you're a fan.
By far the best Jedi there
I chatted to another fan during the intermission and she had this plush... something... dressed as a Jedi. His little sword glowed and if you pressed his other paw, it made the zhooooom-zhoooom noise.
Somehow the plushie got a photo op with opposing combatants...
...and appeared to broker a peace!
Also posted on Dreamwidth, with comments.