"A friend of mine is thinking of running for state office: if he wins, does that mean I can't treat him to lunch if I'm in Madison?"
Sure you can. But you can only do so if he is the representative from your own district or, if not, that you do not have more than six (IRRC) contacts with him or members of his staff during a six-month period, and that you are not remimbursed for any of your activities, other than actual expenses. If you're from his district, and you are not reimbursed, you can talk to him 24 hours a day.
So, let's say your friend is from your city. You drive every week to Madison to talk to him about concealed carry, and you buy him lunch every time.
That's fine.
OTOH, let's say the WCCA pays you for even a tiny fraction of the time you missed work while driving to Madison.
Red Flag: you're now a paid lobbyist. You must pay an $850 a year fee, file quarterly reports detailing mileage, expenses, percentage of time spent lobbying, and a long list of other boring details.
Let's say that your friend is elected to the legislature, but he's from outside your district.
You can take him to lunch all you want. If you buy him lunch, and you've visited with him more than six (again, IIRC) times during the previous six months, you're okay as long as you weren't paid a dime for your time.
Take a dime, and you get to file endless paperwork. Unless, of course, you only spoke with him six times in six months while he was the representative for your district. Spoke with him more than the law allows? Go back to the Registered Lobbyist square.
Clear as mud?
Where things got a bit hairy was back in April of 2002 when we had that fund-raiser with Massad Ayoob as guest speaker. I made sure that all of the politico's there paid the actual cost of the meal, so we were above board. Then Senator Zien arrived with his wife, and I didn't know what to do. It would have been cheesey to ask her to pay the $35 to be with her husband at the dinner. Fortunately, somebody offered to buy her a ticket, and that somebody was not paid a dime by the WCCA, and had only contacted his representative X number of times.
People always say that it's the State Ethics Board that has created these rules, but I really think it was the legislators who did so, just so they wouldn't have to speak to their constituents.