New to Mold-Making: Questions!

[RayChii]

I've just started making moulds (an hour ago!) with a set I bought that uses silicone rubber, and I have a few questions!

How do you clean up the uncured silicone? Can leftover silicone in plastic pots be cleaned, or must the whole thing be thrown away?

I'm using Lego to make a box to pour the silicone into, but I'm finding that it's prone to leaks, what can I do to plug these leaks up?

How can I make sure I'm making the right amount of silicone? Is there anyway to estimate or measure the volume of the mold?

Is there anything else I should know before I go making my next mold?

Thank you very much for your time!

[paulson games]