1)
To what evil do they run?
1.
Rashi: They run to harm themselves, and do not put this to heart.
2.
R. Yonah: They sin and damage everywhere that they go. This is why I warn you against their company, even if they are not going to steal or extort. Verse 11 already warned not to join to them to steal - "Ne'ervah l'Dam Nitzpenah l'Naki Chinam."
3.
Malbim: It is to steal. The father begins to teach his son something easy to understand, that theft is evil.
2)
Why does it add "they are quick to spill blood"?
1.
Malbim: They will kill also you! Do not think that you will escape - they will hurry!