I’ve attended Mormon services, Mormon funerals, Mormon weddings. Always welcomed with open arms.
The only thing that is restricted to Mormons in good standing are Temple ceremonies, mainly sealing.
You can attend the wedding if it is a Civil Ceremony. A lot of times they do this for the specific purpose of having the relatives etc. in on ceremony
As far as the Temple sealing and Ceremony goes, no yu are not allowed to attend.
I'm going off of what I've been told by multiple mormon acquaintances. One of whom was a convert whose parents were not allowed to attend his wedding. That struck me as extremely odd, I couldn't imagine my folks not being allowed to attend my wedding. So over the years I've asked more about it from mormons I've worked with and had reason to associate with, as I'd like to try and at least understand a bit. I've known and worked with many dozens over the years, some I considered friend.
I grew up going to several Protestant denominations, and can't imagine ever being turned away from a worship ceremony. Or a wedding if you were invited. I've even been to mass.
Like Etoh said, the wedding ceremony can be performed in the Temple, or in any other place that the couple chooses. The sealing ceremony is performed in the Temple, members only for that one. More and more couples are choosing to be married outside the Temple, so all their family can attend, and then be sealed in the Temple at a later date, or even later that day. It's always been possible to do this, but wasn't very popular in the past.
As far as the 100 Billion number, that came from a "Whistleblower" who was trying to get the IRS involved, so he could get a cut of the fines. I have no doubt the LDS church has plenty of money socked away, but probably not 100 Billion cash.
