Thanks for the workarounds.
1) Sort of works but not really as expected. The initial opacity is changed, but they all fade to 0 at the same time. Meaning that a particle that has an opacity of 50 and one with an opacity at 100 fades to 0 in the same frame. Looks very unnatural.
2) Angle of the particle, not spray cone.
3) That works, though it's not very optimization friendly and gets messy with bigger projects, which is what I'm trying to avoid. If you have 5 particle objects and decide to change a few settings, you would have to change them on all particles.
4) Yup, I can destroy the particle emitter when there are no more particles. However, again, in a big project with lots of FX, this creates a lot of events. Seems like a "destroy emitter on timeout" property would speed up workflow.