Q2 is also about paying for send from addr2 using unspent outputs from addr1.
I think it could be done with Bitcoin API, as it’s been possible on Bitcoin for some time now. I’ll try to find that old post.
I think it’s this one: [REQ] Send-to-Many in a single tx
Off Topic: Counterparty will support Segregated Witness. With it to fees will be lower.