On your comment about the Ottoman caliphs, sure, I agree that they used the ulama. However, it's also instructive to look at when they started to go "off". Take a look at Murad II (aka Murad the Mad) and his "reforms" for an example of this.
Are you talking about Murad IV? I'd actually use the Ottoman time period during that time as a good example of ulema independence vs state authority, specifically in their collective refusal to endorse the war against the Shia Safavids as a jihad.

We'll have to agree to disagree on this one . I certainly do agree that much of the divinity was shifted to a discarnate locale, but all that did was to shift the communications chain one link further away. The ulama certainly became important, partly as the "voice of the community" and partly as the "intermediary to God". Still and all, that didn't change the basic God-King complex, it just shifted its focus so that you now had multiple people "speaking for" the God-King.
Eh ... very iffy IMO. The ulema do not represent anything like a priesthood in that there is no claim to holy writ in their opinions, thus removing the "intermediary to God" aspect that one finds in Roman Catholicism. You could almost make that argument with regards to Sufi masters, but since most Sufis orders reconciled with the ulema centuries ago I'd even doubt that one. If the God-king discarnated, it discarnated to the Quran, I suppose, but it's tough to get a holy kingdom when you're being ruled by a book --- see the difficulties the Saudis have had, in which the clash of religious justification for an earthly kingdom has resulted in widespread Islamist mockery and hatred for the Saudi royal family.

I think reaching for the Bhagavad-Vita as an argument for suicide terror is even more of a stretch. If you're going to go there, you'll have to include nearly every belief system which justifies (1) action (2) belief in righteousness.