The specifications on the motherboard you selected says that it is equipped with 8 usb ports, more than enough I believe.
Are you going through with building it yourself though? If you aren't comfortable with something like that, you shouldn't have us force you to do it.
As for your list, if you're building this computer yourself, you still need an optical drive and an OS.
To address your query regarding memory, motherboards typically only have four slots available for RAM, I'm not sure if I'm interpreting your sentence correctly, but if you have 4x1GB sticks, that will be the maximum amount of RAM that it can take, with the number of slots being the only thing stopping you from adding more RAM. Upgrading RAM is easy enough though, should the time come that you think you need more RAM you could just swap in a 2x2GB set.
Hope that answers your questions to this point.