Please note that you can change your votes at anytime so don't be afraid of casting a vote. As you learn more about a witness you might or not change your mind.
You need to go to one of the witnesses pages like https://peakd.com/me/witnesses and checkout the witness description, then click on the link to their witness announcement and learn about them.
Hard to say. Best for what? Best for who?
Please note that you can change your votes at anytime so don't be afraid of casting a vote. As you learn more about a witness you might or not change your mind. You need to go to one of the witnesses pages like https://peakd.com/me/witnesses and checkout the witness description, then click on the link to their witness announcement and learn about them.