Re: Is it imperative to do starting strength when beginning Crossfit?
+1 for Matt Corley.
You will likely expect to see strength gains with CrossFit - but your real benefit will be with the MetCon. With your current numbers you shouldn't have any trouble with any of the WODs as Rx'd.
I wouldn't bother looking at CFSB yet though - give that at least a year or two. If you are concerned with strength at all, add in a 5x3 or a 3x5 on Day 1 of the 3 on 1 off before the WOD with one of the major lifts (Back Squat, Dead Lift, Clean, Press, Bench Press). This should give you additional strength gains - but really, this new to CrossFit, you probably don't need them quite yet - you might want to wait to add additional work to the WODs until you stop seeing linear gains.