Some of the channels in the red zone in your list are coming from different directions than the other Philadelphia stations. If you are trying to get those, you will need an antenna rotator since the antenna would need to be re-pointed to get these other clusters. I don't think it's worth it to go this route, so I'd stick with just the channels in one direction.
You should not use an amp in your situation because the strongest channels are too strong for most amps to handle. An overloaded amp will distort signals, so you're better off without one.
For reception down to channel 6, you'll need a full band antenna. I'd recommend something like the Winegard HD7080P. It's about 7.5 feet long and 9 feet wide, so you'll have to check if you can fit it in your attic and have it pointed south-east toward Philadelphia.
When you split the signal to multiple rooms, be sure not to leave any open unused ports. This can cause signal to be reflected back into the coax and has the effect of adding interference to the other endpoints in the network. If you end up with extra ports on your splitter, cap them off with 75-ohm terminators (like
this).