adding keywords surrounded in h2 or marquee tags

1. I wanna put some relevant keywords in pages surrounded in h2 and marquee tags. Is it bad SEO-wise?

2. I wanna put 500 keywords in marquee tag (width: 10px) in home page in footer. what about this? is this forbidden by google?

3. I wanna create 100 articles, each for a city. the content of them is similar, only the name of the city is different in them. but each has its own url. what about this one?