Thanks for your kind words about Meteor Blast!..
The collisions are indeed present, But I have also noticed it is sometimes difficult to hit the smaller rocks with your laser, although I can crash into them easily enough!!, I will probably address this in an update by increasing the collision box around the smaller objects.
Chrome Web Store..
Its pretty easy to upload stuff there, you have to pay $5 for a developer licence, but thats all, theres no approval process, once you publish something, its live! The good thing about it is when you upload an update, users who have installed the game into Chrome get the update straight away, they dont need to re-download or re add it to Chrome!
The banner is one Scirra provide once you publish a game in the arcade (think you have to have a certain number of points before you can use it)
Hope that answers your questions, and let me know if you want to know anything else.