Are actual player FP results available for previous dates/weeks?

Yes, they are!

NFL:

Actual results will appear to the right of the "Proj FP" and "Proj Val" columns typically by Wednesday for the previous week. Use the week selector to go back to previous weeks where games have completed to see the results.

NBA/MLB/NHL:

Actual results will appear to the right of the "Proj FP" and "Proj Val" columns around 3:00 AM ET for the previous date. Use the date selector to go back to previous days where games have completed to see the results.