700x23c is the standard size for a road tire. I have no idea what the c stands for, but the tubes you bought should fit. 700x23c is just the size of tire (I think the 23 is the width?) and the psi is how much air pressure you can put into it. Any good floor pump should have a pressure gauge on it to let you know how inflated your tires are. Definitely need one of those for home use as you should be airing up your tires (or at least checking the pressure) before you head out on every ride. Properly inflated tires make a world of difference! I would recommend starting at 110 or 120 psi as most people seem to prefer those pressures.

I actually thought about you today because one of the fellows I was riding with this afternoon had one of those pumps meant to attach to the bike, but he carried it in his jersey back pocket. You could always try that.

The CO2 I use is Genuine Innovations 16 gram cartridges. I don't think the brand really matters. All that matters is that you get the right kind of cartridge to fit the CO2 dispenser. My dispenser fits both threaded and threadless cartridges. Typically one thing of CO2 is enough to air up your tire sufficiently to get you home safe. Makes your valve stem get all frosty which is kind of neat too. I don't think they expire - it's just compressed gas and I don't think the cartridges should leak or lose pressure over time either, but I could be wrong on that.

Hope that helps!