To Exit or Not to Exit?

Before I go on for a paragraph or two, I'd like the record to reflect that there are many, many things I don't understand about the EU Referendum.  For all my love of England, I'm fairly clueless on this one.  I've tried to read articles and do the research, and yet it's still not making sense.  So be forewarned, if you do understand what's happening in England tonight, the next sentences may make me sound like a dunce.  I'm really not, just confused that's all.

For starters, the whole act of a referendum in the first place is totally alien to me.  A few months ago, there was a Scottish referendum on whether or not to leave the UK.  Now there's another for leaving the EU.  How do these referendums get decided on?  I know people vote on the actual referendum, but who is the deciding body that makes the decision for what the country will be voting on?  For an entire country to secede from a union, seems like a HUGE deal.  Was this a parliamentary decision, or did one of the parties just decide that it might be fun to completely re-write geography, finance, and history because they were bored?

And that's not even addressing the point of leaving the union in the first place.  I understand why some Scots wanted to leave the UK.  They wanted to exert their independence and stand on their own feet.  That I could see.  But in this case, the UK is already its own independent country.  They don't even have the same money system as the rest of the Union.  There doesn't seem to be an upside to leaving. What's the point?  

Finally there's the reporting and opinions on the referendum.  From what I've read, seen and heard over the last few months, no one has openly said they want to leave the EU (except of course the politicians - I'm speaking more on the public in general).  However, in the exit polls that I'm watching right now, it looks like the country is split almost 50/50.  It's pretty close.  Of course, on one of the paper's front pages for tomorrow, there's a quote from a pro-Brexit politician conceding the vote to the Remain-ers.  I'm confused.  Don't all the returns have to be counted first? Shouldn't he check with the rest of his party before he goes about waving a white flag willy nilly?

Like I said, I have no idea what's going on.  In my opinion, without a shred of understanding, I like the idea of staying in the Union.  How different would it be for the Brits to not have the ability to freely travel around Europe?  Passports and visas would be a bit of hassle for members that have never had to deal with them before.  Also, they're pretty much already getting the best of both worlds - support from the greater Union and their own government & financial system (which is doing better than a lot of places, it must be said.) 

But then again, there's every possibility that I'm wrong...I suppose I'll just wait to hear what Twitter says in the morning to determine my real feelings on the subject : )