Lowered trucks and suspension issues:

[CochinoFilipino]

My trucks been lowered by a PO. I don't know how much or what method was used. It drives fine, and there are no signs of bumpsteer, funny noises or anything.

Being a newb here, I'm just looking to learn something about diferent the set-ups and options for these tucks.

I know you can just heat/cut/replace springs to get it in the weeds. But that's not what I'm looking for.

I'm looking for general rules of thumb to abide by to make sure a truck is lowered the right way?

How far can you go with stock parts?
When drop spindles are needed?
Any point where you start stressing the ball joints?
How about relocating the upper control arm for faster camber gain?
When you need to start modifying the stearing linkage?
And the reasons why?

Thanks,