>1. Are these generic, broad "idea" patents and hence there is nothing Google/OEMs can really do here to avoid licensing them? If not, why don't they use an alternative implementation to avoid the conflict?

no alternative implementation would help as it is not about some specific patents, it is more about [litigation] threat that some patents in the vast portfolio can be found that may be in some sense considered violated. Basically it is racket called Android Licensing Program - you pay "protection money" to MS in exchange for it not bothering you.

What interesting here is that Google seems to leave its OEMs to fend for themselves, thus instead of fighting one Google over 2B/yearly pot (the show that first row tickets for would sell like for Superball), MS extorts fifty million here and hundred million there which is much easier and safer.