Walts bread crust thing

I'm in the middle of s4e3 so please no spoilers.

Whats up with walts bread crust thing? I've seen people on this sub saying he got it from someone he killed?

I've also seen people saying he gets something from everyone he kills? What did he get from those two meth slingers he killed to save Jesse?

Bonus question: why does walt write his name on his brown paper lunch bag sometimes?

Please enlighten me, thanks

Submitted July 27, 2017 at 12:25PM by Blacklivesmatthew http://ift.tt/2uGq2gA