Can I use one Active Eye at the top of my driveway to trigger a second Active Eye somewhere in the middle of my driveway which would turn on my lights?
No; you can't relay the signal this way. From what I experienced, the triggerable viewing range of the ActiveEye is a long distance. I had to reposition my front yard one so cars driving down the street would not give me unwanted triggers (~50ft.). So you probably don't need to have the ActiveEye right at the end of your driveway, but maybe further up and still get coverage at the entrance.
P.S. There is also the Passive Repeater you can try:
Boosting Signal StrengthThe Active Eyes are RF and from what I've been reading I think the PR511S are powerline. Would I need some kind of transceiver in the house to actually control the lights?
Yes you do need a transceiver to convert the ActiveEye's RF signal to a Power Line Command to control lights.
How loud is the SC546A remote chime?? Would I need one on each floor of my house?
They are definitely loud, so it depends on the size & construction of your house if you would need more than one.