as for #1- i dont think they wanted to wait that long and risk the Don being killed, by the time they feed it to the papers and it is well written and action takes place it could be a day or two which could be too long and Solozzo may have suspected something was up, I mean look how long it took to "cool down" after the killing from the papers. Youcant just have one paper put it out u need a few.

and as for #2 Im sure his father didnt ask Micheal, Micheal pronly wanted it, i mean, if Micheal didnt do it im sure maybe Clemenza or TEssio could have took it over. as said by roth "This is the business we've chosen."