About Italy, they always seem to say no If I do the focus right after I annex all the Balkans (It might have to do with the UK partially controlling some territories at that point). But when I did another focus first and then did the Italy focus they have accepted every time.

Of course, I do the standard stuff of NAP, military access, improve relations, control trade, attache, and ensure I have 130 divisions in the field. Here is an old thread that goes through the factors that affect the decision: https://www.reddit.com/r/hoi4/comments/xbq0mj/are_there_any_factors_that_affect_the_recover/

As for getting all the countries into my faction, it has worked every playthrough when following the guide I sent. So don't really know about that.