Thanks for replying. Keep in mind you're the one doing me a favor by responding. 
Not a favor at all. It's my duty to tell a friend what I know.
You mentioned 2 great emams who were nominated by their peers because of the knowledge and dedication. Does this mean there are no living emams in Sunni Islam? Or are there more scattered around, perhaps teaching at at Madrassah? BTW, did you attend a Madrassah yourself?
They are two kinds of Imams, the great Imam & the Mosque Imam.
There are countless Mosque Imams 'living', but Muslims around the world have not instated a ruler (great Imam), and I don't know if there is one living that will be made a ruler of Muslims.
I never studied Islam academically other than that in Saudi schools (very narrowed down knowledge), except for an elective course on creed in my English B.A.
My Sheikh is books, and my Madrasah is the library (& Google

)
With respect to marriage:
1) What is the role of a guardian for a woman and why do you believe one is needed? Does the guardian have to be a man?
The role of the guardian is accepting the man to be a husband of his female family member.
Women can be swain by unworthy men as we all know, more likely than men to be by unworthy women. If a man is immorally fit, the guardian is supposed to decline.
If the guardian forbids his female relative from marriage or is unfit for any reason, the justice system should take care of that, and the judge become the guardian.
2) Man married his relative?? I'm confused.
I meant to say the guardian giving his female relative to a man 'in-marriage'.
3) Acceptance from the man? Isn't he the one who usually proposes marriage to the woman, and even more so in male-dominant societies?
yes, this is how it goes in Islam, after proposing and such, when marriage is becoming official, the Islamic way is the bride is given, and the groom accepts.
4) I'm not clear about what your definition of "dowry" is. I'm under the impression a dowry is something a man pays the woman's family for her hand in marriage, almost like a purchase. This may not be what you're referring to.
Yes, it's anything owned by the man that he gives to his wife to be married to her.
It shouldn't go to her family, it's hers to keep, unless she gives by choice.
It's not a purchase in anyway. It's a woman's right in Islam.
5) As for making the marriage announced, does this mean there is no ceremony? It's a simple matter of moving in together, making a few phone calls and telling everyone, nothing else?
No compulsiveness in the type of ceremony for marrying in Islam.
The minimum is slaughtering a sheep, and inviting others to eat which is a sort of announcement, or you can do it over the phone or inviting people to Taco Bell.
This is the legal side in Islam, and different Islamic cultures have their own types of ceremonies.
Does this also mean you can get unmarried in the same way?
Divorce in Islam is a whole other story. It's complicated to explain.
It's a 3 strike policy with return possible. It's a decision of the husband.
The woman, if for any reason, whether legitimate or not, wants divorce, she can ask for it, or file a case in court if the man is an unfit husband. The results & the type of divorce differ, as in some cases, she needs to give back the dowry in order for the marriage to be dissolved.
I'm not an expert on this matter, and I really hate family separation as I've seen what that can do to kids, but 'stuff' happens as we all know.
Just trying to understand.
And it's always a pleasure to answer with what I know.