Does anyone really know what happens in the afterlife?

Not exactly, since no-one alive on Earth has every experienced it, or anything remotely like it. We can describe it in various ways, like "perfect happiness forever" or "total fulfillment as a human being", but again, no-one on Earth has ever experienced either of those. So, we just trust in God, Who does fully understand it, and offers it to each of His beloved human children.

There is no afterlife.  Dead is dead.  So make the best of the life you have now.  Don't waste it down on your knees.

Yes.  What is called the "near death experience" has been reported since ancient times, and described, pretty much, in the same way as they are today, across cultures and geographic location.  It's been a fascination of mine since I was young, and used to long to meet someone who has had one.  I've since met several, and they all tell me what I pretty much expect.  

The first was a good friend of mine, who finally told me about his experience, after years of being friends.  It wasn't something he told many people out of fear of not being believed.  He didn't know of any instance of others experiencing the same thing, or that it was a subject I studied up on.  As he was telling me his account, I was asking him if he saw 'this-and-that", and finishing his sentences before he got to. 

It's not something I can say I've experienced firsthand, but after all the testimonies I've heard and research on the topic, I have no reason to not to believe in it.  I think A&E channel had a show called "I Survived: Beyond and Back", sometime ago, and you could probably find clips of it on youtube, along with many personal accounts, even from former atheist.  

No.  If there actually is an afterlife, there is no known way for information from that afterlife to be sent to this living world because it would be in some other plane or dimension of existence.  So, anyone who claims to know what happens, what a person would experience, or what is there in an afterlife is speculating at best, or more likely just making sh!t up.  Every religion makes some claim about an afterlife, and none of them have any verifiable evidence to back it up.

Does anyone really know what color the teapot orbiting Saturn is?

Not all of it, but Christ has sketched it out for us, principally in Section 76 of The Doctrine and Covenants.

no people just guessing that's all.

NOT YET BUT GOD HAS COME UP WITH SOMETHING SO GREAT THAT THE BIBLE SAYS IT HAS NOT ENTERED INTO THE hearts of men what God has prepared for us!! Meaning born agains wow!!

Purgatory is temporary torment by fire.  Those in purgatory are called the Church Suffering and must be purified from sin before being permitted to enter heaven.  Their sentences there can be diminished by the prayers and sacrifices of people still living, i.e., the Church Militant.

People that were legally dead,& were revived back to life,say that there is a real

Heaven & Hell.