Thank you :) So, I can use my old mouse? What about my old keyboard? I think the mac ones are not very ergonomic. I have a Microsoft wireless mouse and keyboard that I’m so much more used to.
There should be no problem.
OS X will recognize almost anything USB. Just plug it in. Within a few seconds (the first time and instantaneously after that), it should work fine.
Sure you can! Try just plugging them in and see if they work. Since they are Microsoft, tho, chances are Bill wants you to have to download some drivers for them.
Don't be afraid to mess around with your Mac. They are very tolerant, even of 3-years olds (don't tell my kids I let their kids play on the blue and tangerine iMacs!)
Use whatever USB mouse and keyboard you wish. If you have some non-USB interface peripheral, likely an adapter will work.
You can also use whatever monitor you want. If you have all these, you can get a new Mac for about $600.