1. If it's a fictional metaphorical use, do you need to deal with trademarks? (I.e. The man swung on the rope as effortlessly as Spiderman.) What about things like Disney or Harry Potter? Can a character say, "Who do you think you are, Harry Potter?" or "You're about as sweet as a Disney cartoon."
2. What if you're using like a quote from another book or person as a chapter header? Besides listing your source, do you need to do anything else?
3. With pop culture, do you have to be careful when using either living or dead celebrities? Frank Sinatra makes occasional appearances in some of my books, but it's in dreams, and I'm not portraying actual events. What do you think? Does the way a celebrity is portrayed (negatively or positively) make any difference if you're not claiming it's non-fiction?
4. Also, should you shy away from using terms that are brand specific for any reason? Kleenex, Taser, Coke, Googling, etc. I guess you run the risk of being "dated" in some cases, but it sounds odd if you don't.
I don't want to clutter up things with trademark issues or deal with the nightmare of rewriting characters to avoid nastiness. Anyone have any thoughts on this?