Wait, Precinct Under Siege has a second wave? I've been clearing it by turn 6-8 by killing the ogres and killing the mooks fast enough to panic them all.
Yep! It came as a surprise to me too. It's not difficult to clear out the enemies before that final wave spawns, so I didn't even know about it until I went exploring the data files/Xpedia and learned about it. I had a similar issue with Zombie Panic with capturing the Tomb Guardian, and I don't think the extra advice from the Fire Witch existed back then either, so I was completely lost on what to do with that mission chain. I know better now, but I was very confused at the time.
What are the conditions for mission "Wasteland Trouble" to spawn? I had one in first month and another one in second month. I'm in 7th month now and I've not have any more of those missions. I've notices 2 times spawns of 4 bandit cars with "causing trouble" mission objective heading straight at my base, but in both times I cleared them out. Re they related? Should I have let them roam free?
There is another new activity. A 100 speed contact that usually spans in batches of seven to look for your base, but it was alone. Would it spawn a mission if I let it roam free?
To my knowledge, the Wasteland Trouble missions spawn based on whether you have a base present in each of the various regions of the world (e.g. North America, Arctic, SE Asia etc.). There's a separate check for each of the regions and the script controlling the mission spawn will run once per month for each region with a base. It's about a 17% chance for a spawn per viable region, and they stop spawning altogether by Jan 2602.
The four bandit cars that spawn together and target your base are completely unrelated. That's a base attack mission being generated and has nothing to do with Wasteland Trouble.
The contacts at 100 speed are another base attack mission. Those are roving bands of ratmen and if they find your base you'll be attacked by Stormrats. The roving bands make you lose score while active, like most hostile contacts, and are very easily destroyed with accurate weapons (20 dodge, 1 health, no weapons).
EDIT: If you only saw one of those roving bands present, I have no explanation other than you didn't detect the full batch of eight. As far as I can tell from the data files, they only spawn for that mission and only as a group of eight all at once. They do spawn spread out over the targeted region and each has to be individually detected, which occurs at 30min intervals, which can confuse matters.