I am seeking help on few things

1) I am installing a siren and strobes where is the best to run the positive wire from? the battery or fuse box

2) where is the best place to find a hole thru firewall?

3)I just purchased fog light for my car I got a Ford factory foglight. Never had them installed I only have the round holes in bumper ready to be cut out. Where would I find the wires that were installed in the factory?

4) where can I hook up the siren speaker best?