"When a casino release LE's in the US how do they do it exactly? Do they just distribute the chips from the cage randomly, sell via a retail outlet or what? do they inform collectors?"

Different jurisdictions have different rules. In Las Vegas they are sold at the cage. I believe there is a rule some must reach the tables. I think one chip may be sufficient.

In NJ they are sold from a roulette table set up for the purpose of the release.

There are some variations also to what I just said.

Chips are not allowed to be sold from a retail outlet.

Most casinos do announce a release. In Nv. there is a gaming report every month that is released and lists what chips have been approved or declined.

Barry