I decided to do some testing and got all the answers I needed :D

I killed all enemies at the same time with the console command from the wiki, but using entity.die() instead of destroy(). https://wiki.factorio.com/Console#Kill_all_enemies
That way the events on_entity_died and on_post_entity_died ...

For the mod I'm writing I like to use all the data in on_post_entity_died for when the player/character dies.
The only problem is that there is no way to get the player who died. I know that the corpse in the event contains character_corpse_player_index but what if there is a mod installed that ...

Oh haha, it already exists.
Probably way better made than I would be able to
Thanks! I'll go check it out.

You can read the contents of the full train via the train stop, but what if you can read the contents of an individual cargo wagon?
This might help with making balanced train (un)loaders. I barely use circuit networks, but if people like the idea I can try and make mod out of it.

You can't connect ...