Basically all councillors are party members, it's very common. Michael Spadafora literally ran for the conservatives in the provincial election.
Councillors associating with provincial and federal parties is not illegal at all. What they aren't allowed to do is during an election say "I'm an NDP councillor" - which no councillors have done.
Outside of election periods, councillors are free to associate on a personal basis with political parties, and many do. Including conservative councillors.
Councillors typically work well over 40 hour weeks and as far as we know Kroetsch and Nann were taking personal days. Those exist, you know. Given Kroetsch's openess and how often he expresses virtues of being honest about things like this, I would be extremely surprised if that wasn't the case.
Hamilton centre is actually likely one of the poorest ridings in the country.
This map shows incomes across the province, and you can see how much noticeably lower they are in downtown Hamilton. Downtown Hamilton is full of subsidized housing and old apartment blocks which means it houses many of the lowest income residents of this province. There is a small enclave of wealthier residents south of Aberdeen, but the rest of the riding is very low income. Many of these areas had median household incomes below $30,000 in 2015, compared to the Canadian average of $70,000 at the time.
Generally the wealthiest areas of the city are in Ancaster.
https://censusmapper.ca/maps/838?ind....2653/-79.8641