Convert Month Into Its Number Equivalent...(Ex. JAN=1,FEB=2...)

Good Day to Everyone,

Need help!

I have this SQL table w/ fieldname "PayPeriod". Sample value of PayPeriod are SEP06-1, SEP06-2, OCT06-1, OCT06-2... Wherein the first 3 chars is the month, 06 is the year, 1 or 2 is the cutoff where 1 means the 2nd half of the previous month and 2 is the first half of the current month.

Now my questions are:
1.) How can I select these values sorted according to date. Since this is a character data type. Sorting is alphabetical. I need to sort it according to date where JAN05-1 is the first record and the last record is DEC06-2 (assuming that the oldest year is 05 and 06 is the latest).
2.) How can I convert the 3 char month into its number equivalent. Example, JAN is equal to 1, FEB is 2, MAR is 3....
3.) How can I count the no. of days in a month? Is there a function that would result to the no. of days in a given month?

Thank you so much in advance. :)