4.Threaten to use the combined Google+Motorola patent portfolio against Apple products like the iPhone and iPad unless Apple stops suing Android vendors. This is good for Google since (if Apple does the deal) it means less risk of being sued over Android and less patent royalties that would need to be paid. Good for consumers since patent royalties increase the cost of devices.
Even better would be for Google to create an Android defensive patent pool. Anyone working with Google on Android (including HTC, Samsung, Dell, LG etc) would be able to join the pool with any mobile device/OS/etc patents they want to contribute. Google would contribute relavent patents from the Google pool plus whatever the new Motorola pool has. Any Android vendor that is sued over an Android handset gets to use the entire Android patent pool as a counter-attack.
A patent chest isn't like a sword, in that you can't just swing it at people you don't like. You have to, you know, like have an argument that your opponent is infringing on one or more of your patents.
As for your talk of a defensive patent pool, the difficulty of this type approach is that is generally requires patent holders to surrender some control over their patens and if the patents in question are ones that bring in revenue through licensing, then companies are generally reluctant to do this.
It also may have escaped your notice but Google have shown absolutely no interest in assisting companies who are being menaced by Microsoft and Apple so the test here will be waiting to see if Google will revisit this 'silent partner' now they have a sword. Exactly how sharp that sword is, remains to be seen.