For numbers 2 and 3, suite upgrades and free suite nights are in most cases confirmable only for entry-level suites. (At the GHK, this is a "Garden View Suite.") If entry-level suites are sold out for your dates, you cannot use the suite upgrades or the free suite nights, even if higher-level suites are available.
Of course, you might get upgraded to a higher-level suite at check-in -- in fact, quite often, you will -- but you cannot confirm into such a suite in advance. I never had a problem using my upgrades or free suite nights, but I was usually able to plan in advance.