I'm wide awake and bored so I'll wade in with my thoughts:
Do you have to be a fan of the original artist, or maybe you become one? - I don't think you have to be a fan, but I would say it helps. If you're a fan, you will come pre-configured with a certain amount of knowledge of the material which should make things quicker to get rolling. So, not a necessity in my experience, but it's handy.
How important is it to be visually/musically identical? How much latitude are you allowed? - I think this very much depends on who you're tributing. If it's KISS, you're rather obliged to go 'all in', but if it's Eagles, who cares?
Do you ‘get into character’ or is it just a gig? - Again, I think it depends who you're tributing. It was difficult for me to know which 'character' I was supposed to be getting into as I was the bass player for a Bowie tribute. I had a Gail Ann Dorsey Stingray tribute hanging off me, but I'm not black or female, I don't wear skirts and she was playing a lot of material that was originally played by others.
Does it feel musically limiting, or is it fulfilling your needs? (Maybe you have a side band?) - Personally, it never was. It was always a challenge. We had a high turnover of not difficult, but not particularly easy songs in the catalogue which had various arrangements attached to them. With my other bands, it always kept me busy.
Do you have any qualms about tributes ‘stifling original music’? - None. We played. People paid to see us.
Have you ever met or been seen by a member of the ‘originals’? What did they say? - Live, not to my knowledge. We were seen by some hardcore Bowie fans over the years and they're known for being hyper critical. They liked us.
What is the overriding thing being in a tribute act has taught you? - You can't please all of them. There's always one or two that would say 'Bowie did' this or that on the original although we tried to remain faithful to specific versions of live versions of songs. Some had been adapted by Bowie over the years. Sometimes the key was different to the original (for good reason), the version was truncated/extended or segued. There were always the stick in the muds that lived and died by everything from the Ziggy era, but that's not where we pitched ourselves. We were very much, if Bowie was still touring, this is most likely what you would have got, not what he did 50 odd years ago.
Having done it once, would you do it again? If so, would the musical angle be very different? - Done it once (Bowie), done it twice (Bon Jovi) and I'm about to do it again (Queen). Three not massively different musical angles. It has to be music I like or I wouldn't have the appeal. I honestly cannot wait to start with Queen, although finding a keys player that can also sing good backing is proving problematic.