Question about the LCS Playoffs

So with the playoffs coming to a near, I have a few questions.

1. Are top 2 automatically placed into the next LCS Season?
2. How does a team get dropped from LCS?
3. If a team were to beat the opposing team in the wild card, would they be automatically in the LCS for the next season? Or would they have to beat one of the top two as well?

Thanks in advance!