Is there a way to script the events and actions instead of using the UI?
No, it's events only in Construct 2. You could have a look at coding plugins and behaviors in the SDK, but that's generally pretty involved compared to snippets of script.
s there a way to indicate a color to be used as a transparent color when importing a frame or sprite strip?
No - Construct 2 supports full alpha channels so I didn't think it was necessary, but this has been requested a lot recently, so I guess other software hasn't caught up yet. I'd better add it - it's on my todo list now!
latform Vs. Physics
Physics objects only interact with other physics objects, they ignore other objects completely even if they have the solid behavior. You might be interested in this tutorial on Physics.
Solid and Physics on a single object should work OK though.
layer object passing through floor objects
Generally it's up to your game to make sure the player doesn't get 'stuck' inside solids. The platform behavior won't control your animations or events for you - it'll just try to figure out how to respond to its surroundings, and if it's stuck in a solid it can't really do anything. Your solution sounds like a good idea - invisible detectors are common in games.
Hope that helps!