Congrats! An AK-variant is a great and fun to shoot weapon. On to your specific questions:
Century Arms is a large arms importer and re-manufacturer. Here's what they do:
U.S. Federal law 18 USC 925(d)(3) prohibits the importation of military surplus semi-automatic (or automatic, for that matter) rifles. In order to "get around" this law, Century buys the rifles from the foreign government or their wholesaler (say, Yugoslavia or Romania, both likely in your case), sets up shop somewhere outside the USA--I believe frequently Canada--and "de-mills" the rifles, usually by cutting up the receivers and barrels (importation of barrels was prohibited as well in 2004). Century then imports the disassembled parts--now considered a non-firearm because the receiver has been destroyed--into the USA and then rebuilds them with new US-made receivers and barrels, as well as enough other US-made parts to satisfy 18 USC 922(r) in their Boca Raton, Florida facility.
... I bet you're now scratching your head saying, "Well, that's stupid! Why not just import it as-is, or just convert it to semi-automatic and then import it? That's the most convoluted, ridiculous thing I've ever heard!" It is. Frankly, it's utterly ridiculous, but it is the US law. Thank your nearest federal government representative for the additional cost and lower quality, as well as loss of all collector value in your rifle.
The problem herein is that Century is interested in volume, not quality. They have absolutely no quality control in their manufacturing process, and they seem to employ a large number of drunken and drug-addled monkeys (my apologies to monkeys for this slight) for their manufacturing operations. I would STRONGLY recommend carefully examining the rifle before accepting delivery. Look especially for canted front sight assemblies and/or mis-aligned gas ports--these are common problems with Century AK-variant rifles. I have personally had two Century AK-variant rifles with severely mis-aligned front sight assemblies (the second was a warranty replacement, shipped direct from Century Arms, they finally got it right on the third attempt). That said, rifles from Century can be great shooters, it just seems to be luck of the draw. But I digress...
The Kalashnakov rifle was originally designed for Russian conscript "farm boys" with no education or mechanical experience to be able to successfully operate and maintain. It's probably the most "soldier proof" front-line rifle in the world today. You can find all kinds of information on how to field-strip on the Internet, and you will find that it takes a only a few seconds and no tools. It has few parts and is incredibly easy to maintain (you'll probably end up saying "That's all that's in there?!?" when you take it apart). While certainly not an elegant aesthetic design--that said, I love 'em; beauty is definitely in the eye of the beholder--nor a particularly accurate rifle, it is utterly reliable in nearly all conditions. It's a fun shooter with practical applications as a SHTF (S- Hits The Fan--if you're not already familiar with the lingo) rifle, as well as adequate for small/medium game at shorter ranges.
You should thoroughly inspect and clean ANY new-to-you firearm before shooting. Some may be full of packing grease and machining residue, others may have an unsafe condition that you want to find BEFORE shooting it!