45 minutes from Tribeca to Keniworth is accurate. Assuming no traffic at your time of departure (which is out of rush hour window) you probably can get there in 30 mins.

JFK to Manhattan - 1 hr is accurate but you may wish to route paths alternate to GPS which may add extra highway and miles vs. listening to local FM 101.9 (on the 5s) or 1010AM (on the 1s) to determine if any of the highways you are on have hiccups. You should be fine except for the BQE if it directs you to the Williamsburgh Bridge (FREE) vs. the Midtown Tunnel (TOLL).