The loss of Abukawa had a meaning, he protected Shuichi from being bullied and was close classmate to him, noticing him not wearing glasses back then.
Shuichi will unfortunately loose more people he knows, this will make a bad impact on his character...
Dunno what was Abukawa wish, nor why he got involved with Madoka group, but judging by how they gathered their members, he wasn't doing it willingly.
It's a shame he died in agonizing death, it's all Madoka fault.
Ikeuchi probably gonna switch sides, but until Sayaka contract is in effect, he won't came out alive from that. Should have confessed to Chihiro when he had a chance...