To answer your questions.
A. The only square resistors I know of are power resistors (rated at many watts). If you found 1/2 W 47 and 470 ohm resistors they should work.
Digikey is one of the major suppliers of components online (however you should be able to find those resistors at your local radioshack/electronics store.) If not, here's a link to a digikey search with 1/2 W 47 and 470 Ohm resistors. The resistors are a few cents a piece. (Just make sure you don't try to buy the ones with a 5,000 minimum order quantity.) I'm making the assumption that these resistors aren't special, but they very well may be, so I can only be sure once you post pictures.
http://www.digikey.com/product-search/en?FV=fff40001%2Cfff80482%2C4021b%2C40459%2C80005&mnonly=0&newproducts=0&ColumnSort=1000008&page=1&stock=1&pbfree=0&rohs=0&quantity=&ptm=0&fid=0&pageSize=50B. If you own a multimeter, you can actually check the resistors before you buy them or try to desolder them from the board. Simply place the multimeter into ohms mode and put one lead on each side of the resistor you want to check. If the multimeter has multiple ranges (100 Ohm, 1000 Ohm 10kOhm etc.) make sure you put it in a range that will give you relevant results (1000 Ohms would probably work for you assuming your multimeter has 4 digits.) (You can't hurt anything if it's in the wrong mode for ohms, so no worries.) Do this with the radio OFF and NOT plugged in. (Don't measure resistance with power to whatever you're measuring.)
C. As for articles... not really? Your best bet would be to post the model of the radio or links to the sites where you found the solutions of replacing those resistors.
I find it odd that resistors would fail... My first guess is always capacitors (the big round cylinder things.) But then again, I haven't repaired that much equipment.
I agree with Robert above, if you want our full help, you're going to have to provide a bunch more information, and pictures would be absolutely great! I'd definitely start by posting the model number of the stereo and pictures if you can!