I'll have to look into the first question, but for the second it's very simple.
Assuming you have the platform behavior on the enemy all you have to do is select your enemy sprite, go into the properties panel on the left, in the behaviors properties under platform, you'll see Contol: Default: "Yes". Click on it and change it to "No".
that should do it :)
...and artistic hocus pocus that will leave you up in smoke!