Here's some info on the schedule:
http://www.lexingtonma.gov/home/bulletins/special-town-meetings
It looks to me like the deadline for getting items on the Warrant is tomorrow, 1/7. I would expect that it be published and available sometime before the selectman meeting on Monday, 1/11. I would expect at that meeting the selectman would be voting on each item whether to "recommend" or "not-recommend", and send everything to the town meeting.
Then the actual vote will be at the town meeting, by elected "town meeting members" on Feb 8. Both the selectmen meeting and town-meeting should be open to all residents and possibly non-residents as well. Assuming its the same as my town, only elected town-meeting members get to vote on this issue. All town-meeting members should be allowed to speak on the issues, but might be time-limited. The non-member residents might also get to speak but more limited.
Based on experiences in Reading recently, it will be pretty important to contact each of the selectmen and find out where they stand. Then stress how much of a PITA this proposal will make their lives. There's going to be lawsuits. There might be new people running for selectmen seats and town-meeting seats. This will bring out all sorts of attention to the town gov, that will become a nuisance to them. It will take time and resources away for all the other BS that they want to do in town. We still don't have the exact wording of the new ordinance, but is the Lex PD going to go door-to-door with the confiscation van? What is the town prepared to do if otherwise law-abiding citizens(checked and licensed by the LPD) who've owned an item for 20 years, don't want to give it up?
In my town, the selectmen and town-meeting members generally like things when very few people are interested and show up to vote,and show up to meetings. If you look at the last election results, you'll probably see that some seats are only won by a handful of votes. There are a bunch of town-meeting members here who only get a couple of votes TOTAL and win their seats, and there are open seats sometimes as well.
In Reading, the selectmen were much more sensitive to the resource drain issues than the town-meeting members. The town meeting members seemed to be either for or against strictly on principals. The town-meeting members meet only a few times each year, but the selectmen meet every week, and don't want their weekly meeting bogged down with issues like this.