On the outbound, your luggage will be checked all the way through to TLV and you will not need to recheck it anywhere along the way. It is only on the return where you will have to claim your luggage in PHL, go through immigration/customs, then recheck your luggage to SMF. Your luggage will already be tagged to SMF so all you actually have to do is drop it off on a conveyor belt as you exit into the terminal.

I've never flown US to TLV but have connected in PHL several times to CDG and LHR with no problems. As far as my experiences have been, 2 hours should be plenty of time to connect.

Since you're flying in the winter, you never know what the weather may bring. So...if I were you, I'd simply stick to the most simple/direct routing. Since US only has 1 daily flight to TLV, any problems and you might find yourself sitting in PHL for 24 hours.