If there is plenty of food they will hangout in your garden after a release, with plenty of food sources they might even get comfortable and lay eggs. Outside it’s good to add companion plants to attract them.
They absolutely will. They'll breed like rabbits, too, if they've been eating well. You might need to introduce a new colony if there's a lot of time between grows. But even then they just fan out over the area. Increasing their population is never a bad idea.
I often see a few natural ladybugs, even seen some larva, but never a shitload...might have to buy a bunch and try mid summer.