Hi Gavin and welcome to the forum. To answer your questions:

Drinking beer shouldn't throw you out of ketosis, if you drink it in moderation and if you stick to light. Light beer has about 4 - 5 g of carbs. Also, you body burns alcohol as ketone bodies regardless of whether you're LCing or not.

I would suggest you finish reading Dr. Atkins book, it was not intended as a 0 carb plan. 0 carb plans really aren't healthy. You do need those 20g of carbs from the green veggies ( you need their minerals and vitamins and fiber even more than you need their carbs). You might also be interested in know that unless all you're eating is unprocess meat and oils you have been eating some carbs (there are carbs in cream, eggs, bacon, saussages, coffee and SF jello).

I have heard that quitting smoking while on this WOL is somewhat easier; it also makes the plan work better as smoking causes an insulin rise. Qutting will improve your insulin sensitivity.

HTH
Nat