When I press "C" for Civilization, there's only one civilization there. The tab says:
This land has no important leaders
Is this significant?
That's significant, yes. It means that the civilization your dwarves are from was wiped out. In game terms, it means that you'll only get two waves of migrants, and then no more, ever - which may be a good thing, for your first fort, but it'll make it very hard to put together a military, so you should focus on building walls to keep yourself safe and traps to deal with the goblins without risking your precious dwarves. It might also mean that you won't get any dwarven caravans, which is not a good thing, or that you'll get dwarven caravans from a different dwarven civilization, which seems to mean that they'll come a little less frequently but otherwise isn't a big deal. You'll probably want to make a point of staying on the good side of the other civs' caravans, though.
(Oh, and the fact that there's only one civilization listed just means that the others haven't visited your fort yet, so you don't know anything about them. Each one will show up in the list the first time they send a caravan or diplomat or thief to visit your site.)
Also, yes, I just got a bunch of refugees, on summer (New world :/), and boy do they suck. Five of them, a combination of lye makers, dyers, armorsmiths and....uhhh...whawazzat? Oya, a brewer.
Brewers are important. Thirsty dwarves are slow, unhappy dwarves. Armorsmiths are pretty good, too, if you have the right kinds of metal. (Even if you're not going to have a military, metal armor is a nice trade good.)
Also, when will goblins start raiding? Sorry. I just want to know, if I have a deadline to build defenses....OH
You'll probably see your first goblin thieves after about an in-game year, and ambushes a few seasons to a year after that. They tend to come in with the caravans, and there's often a big siege in the winter. They also respond to your fortress's wealth - the more wealthy your fortress is the harder they'll try to capture it - so if you want to stick to just thieves for a while, don't go mass-producing masterwork stone crafts or anything.
And I think I found a glitch. I was playing along on my new save, when I finally figured out how to make a Militia. So, I go make some training sticks, and go to equip them. In the "Weapons" menu although, there's a lot of weird weapons, Bowguns and Spears. I only started with two copper battle axes, so...These are the names:
Goblin Cap Spear
Blood Thorn Spear
Nether Cap Spear
Tunnul Tube Spear
Blood Thorn Blowgun
Goblin Cap Blowgun
Nether Cap Blowgun
I don't know how I got them, but I now have two speardwarves with...spears 
This isn't a glitch, and it's not really a big deal. It's a bit of a spoiler, though, so I'll hide the explanation behind a spoiler tag:
This means that you have an animal-person tribe in one of your caves. Those weapons belong to them. There'll be some mysterious forbidden food and leather in your inventory, too, for the same reason.
Mostly they're nothing to worry about - they're 'hostile', but not very aggressive in my experience; they won't bother you unless you bother them. If one does try to come into your fortress, check the units screen (with 'u'; scroll down past your dwarves and their livestock) to see whether it's listed as 'hostile' or 'friendly'. There are certain circumstances - basically uncontrollable ones - under which specific animal-people can become friendly to the local dwarves, but that's an even bigger spoiler:
Darn, spoiler tags can't be nested. Well, I guess if you clicked the first one you'd be pretty likely to click this one, too:
If an animal-person defeats a forgotten beast - a randomly-generated boss monster that appears in the caves - that specific individual becomes friendly with the local dwarves. This can be a rather impressive feat, depending on the beast: Some of them are real pushovers, but some are nearly impossible to kill, and animal-person weapons are absolutely horrible in any case.