from what i know an iman is not needed for a marriage ceremony, a pious person is ok, wali is included as the witnesess i mentioned as compulsory, wali doesnt have to be a father or brother, it can be someone who is an elder or someone respectable, in my old muslim community people got married and divorced among friends, some married at the mosque because they enjoyed the ceremony, some got married at home with family, my ex performed divorce with his group of friends as counsellors and witnesses, and i got divorced by his two brothers over the phone, his brother also divorced his wife by letter with two witnesses.. Anyway, thats all i know, and witnessed, i guess it will be totally different in an islamic country under shariah law that is very backwards..
Peace xxooooo
A wali is always the father, then the uncle or grandfather on the paternal side, then on the maternal side, then her son if she has a son from a previous marriage, and if there is no single male relative in her family that has the
right to be her guardian, then the leader of the Muslims takes the role of wali. Some random guy is
not allowed to take the role of a wali, the marriage contract could be argued to be invalid in such a case depending on the situation. If you are in a non-Muslim society, then the local imam who does the marriage contract is the wali of the woman, according to recent fatawas I've read pertaining to the matter (since a lot of Muslims live in non-Muslim societies nowadays). There are, as I mentioned, pretty detailed rules who is who and who can take what role in a Muslim society. And the ease with what a (man) can marry and divorce is not something positive, rather it undermines the woman's rights because she can be tossed away anytime.