Beating an inferno tower

In relation to attacking a TH10 I have some questions regarding how infernos work.

1. Assume a few golems - In single shot mode where it takes up to 5 seconds to fully heat up, once it kills the 1st golem it focuses on and moved to a 2nd golem - does it start at full strength on the 2nd golem or after each troop does it start at low again and have to work up to full strength over 5 seconds?
2. How many seconds does an inferno blast from being fully charged?

What else have people discovered about beating an inferno in either single shot or multi?

Thanks