So I would use the first version of that sentence- "That's a lot of people. How many of these people do you actually see on a regular basis?" But you can use the other version, too. In this case "meet" can mean "meet with", like: I meet with her once a week. (get together, have a meeting, have an appointment, a set time) In your first sentence ("I had up to 900 friends on Facebook, including some people that I only met once and never saw again."), "met" means the first time you saw someone and learned their name, and so on. This is the most common use of to meet, but you can use it to mean seeing someone at a set time as well. Does that make sense?

That's a tricky one! Personally, I would say: shine = something like metal, reflective surface. "The stainless steel shines in the light." glimmer = makes me think of glitter ..but this isn't a verb I would use ever. The only thing I can think of is like a firefly that has a weaker light, "The firefly's light glimmered in the night sky." gleam = also a verb I don't use much, but you might say "The floor was gleaming, it was so clean!"