Congrats on the cab! I started my candy addiction with blast city as well. What is most important is to read up A LOT before tampering with things. I highly recommend joining arcade okatu because the wikis and threads over there are a key resource. There is also a decent blast city thread at neo-geo. For both of those forums you'll need to join to access the bulk of info.
As for your cab, what is probably the most important to know is what kind of monitor and chassis you have. Blast usually have tri sync toshibas with nanao chassis ranging from ms-2930, 2931, 2932, etc. Figure out what you have, read up on those sites, and NEVER LICK THE ANODE CAP!
As for your pics
#1: not sure
#2: that the input/output (I/O) board, most of those empty connections are where a standard Jamma harness with be attached, kick harness, and a few other optional things.
#3: not sure what the 3 loose plugs go to, could be marquee light, speakers, etc. Right near the VGA looking plug SHOULD be the other plug for video over JAMMA (if your chassis is compatible)
#4: again, hard to know without tracing them to where they come from, could be speakers, coin meter, coin register.. a number of things.
#5: Just look up the number of the power supply and see if it's the stock blast one, my guess is that it is. I'd be able to tell from a picture of the back..
or you could look at this to see if it helps (keep in mind this Bass Fishing manual is going to differ a bit, it's still be very helpful):
http://wiki.arcadeotaku.com/images/6/65 ... ishing.pdf