Hi, Stroezie. Good to hear from another Judge Dredd fan and I love what you're doing with your own JD campaign, although I would never attempt something so small.
To answer your questions, as a solo gamer I'm used to playing games that are usually designed for two or more players. The secret is to treat both sides equally, without showing any bias.
The Judge Dredd Miniatures Game rulebook does include stats for vehicles and rules for vehicle combat but be warned, they are very basic. Vehicle chases could be done but I suspect you'd need to house rule them.