Voting power is an indication of how strong your votes are right now. As you vote the percentage decreases. It decreases so that way you can't upvote every post on the site and use your maximum voting weight. Over time, while you aren't voting, your voting power increases slowly back up to 100%. If you've played video games, think of it like an energy bar or a mana bar.

In the votes section, the weights are how much weight that user choose to use when voting on that post. Right now 10000 is the default value on the website, so almost every vote is worth 10000. If you use the CLI wallet, you're able to specify how much weight you want to vote with. I assume eventually you'll be able to do that on the website too.

Glad you enjoy the site and hope that answers your questions!