This is actually kinda annoying. In most cases you don't want to make the candidate sit around in reception for 20 minutes, so you go and get them a bit early. But really, it would be better to stick to the agreed time. Slightly early is good - 20 minutes is overkill (though it may be different with other employers).
LOLwhut? I guess that's an alright thing? Never crossed my mind as an interviewer.
This is about 50% of the job process for us. I work in a team of six and it is vital that we like anyone that works with us. Personality is very important - you don't have to be super confident and all that, just likeable, and not overly introvert.