Does your city have Professional sports teams? If so, what ones?
I'm in Calgary. The only big professional team my city has is the Calgary Flames in the National Hockey League. We have a bunch of junior hockey teams, the Calgary Stampeders in the Canadian Football League and the Calgary...
It depends if you have to pay for that software and how much it is or if you can use the free version. You do bring up some good points but I think if the forum is small enough then you don't really need to use something like that.
This is what I thought of too and what led me to use Mybb forum software for my first forum. All I had to pay was the hosting, domain, and then I had more money to hire a designer to make me a custom theme.
Naw I don't think you need promotion forums these days to help promote your forum. You need good content on your forum and knowing how to advertise other ways. Like that saying goes 'If you build it, they will come'