You need 2 SIP pins for each LED.
You can use this to calculate the resistor values if you know the specs of the LED's:
http://ledcalc.com/The rectangular LED's like you have listed disperse the light well under the caps, the round ones tend to focus it right above them. Most reputable LED sellers will know the output power of the LED's they sell. The more Lumens (lm) or milliCandelas (mcd) the brighter. I have no idea how bright the ones you listed are or what their current ratings are.
Something to be careful of is the current supplied by USB. If you use super bright LED's and supply close to their max current rating you will most likely exceed the current rating of some USB ports and particularly USB hubs. USB 1.0 has a max current limit of 150mA, USB 2.0 is 500mA, USB 3.0 is 900mA and USB 3.1 is 2A.
Multiply the number of LED's by the calculated current draw for each one to get a figure for the total current that the LED's will use. Keep in mind that the keyboard controller also uses some current, so allow a little for that, too.