Select the View menu, on the drop down, select show, turn on grid. That will give you lines every 1/4" or so which will make lining things up a lot easier. Next, I wold select view menu, select snap to and select grid. this will make sure that your items are exactly on those lines.
For the buttons I use the elipse marquee tool, hold down the shift key which generates a circle. You can make this whatever size you want, I've been making mine 1 and 1/8". Once they are drawn and you have the grid on it is easy to line the circle up to have a grid mark exactly in the center. I then add another layer and draw two straight lines that cross in the center.
Make sense? If not, send me some more questions and I'll try to help.
Another tool that can be very helpful is the guide lines. You can create these wherever you want. For example draw a vertical guide line in the middle of your CP and then move whatever item you need centered to that line. Makes lining things up much easier.