Firstly, this is a fantastic mod and I have been having a great time playing it - massive congrats to you itchboy (and everyone else involved) for doing an incredible job. I think any bugs I've had have already been mentioned elsewhere and nothing I've had has broken the game.
Interestingly, I thought the lack of volunteers was a deliberate choice. Going along with the small town vibe, the fact there's only four blokes available makes you choose your resources carefully and make use of mutual aid. Personally, if the volunteer numbers are increased, I'd prefer them respond to the station as I don't like sending things to the scene that I don't have direct control over.
I think this might also be a victim of randomisation - I've had the older tow truck in game once, compared to the newer one about ten times, but it did appear!