Owen, welcome. Particularly as a student with a limited budget(which I can remember)you should minimize what you spend on wires to connect your components. The best minimization would be to zero by using what you already have, wherever possible. Don't worry about banana plugs or any other connectors for the speaker wire; the bare wire is fine unless you're going to be frequently connecting and disconnecting the speakers. As for the speaker wire itself, regular 16ga lampcord which you might already have or can get very inexpensively works as well as anything else up to 30 feet or so.
Next, you don't have to worry about the ambient noise in your apartment cancelling out the gains from expensive connecting cables because there aren't any gains to cancel out. The requirement is for a wire with an RCA connector on each end; until the length would get longer than about 40 feet or there would be some unusually heavy interference that called for extra shielding the usual inexpensive "RCA" type(RCA actually refers to the connectors rather than the cable itself)cable works well for both the sub cable and other connections. This was discussed in more detail in a reply of mine a few days ago by Steve Lampen, Belden Cable engineer. Search his name on the board and read his comments and the other matters that I linked.
The cable you have with the yellow connectors is a 75ohm coaxial cable; the other two(usually red and white)commonly aren't 75ohms, but this makes no significant difference for the wavelengths and distances involved. Any of them are usable.
