Male Ruby-throated Hummingbirds are normally the first to arrive in PA. They'll begin to arrive sometime in mid to late April searching for potential nesting/breeding sites for the females, who'll arrive later on. However, some of these males are simply passing through, as they continue on their migration north to other states. PA's official date for Hummingbirds is May 1st. I'd suggest putting your hummingbird feeder out the 2nd or last weekend in April. Try not to get discouraged if you don't see any hummers at first. Hummingbirds typically prefer temperatures in the 70s and up, which are more common in PA later on in May and June. However, If you keep you feeder clean and with fresh nectar, I gaurantee you'll have hummers buzzing your feeder before too long.
Early Spring
yes you can
yes because it is toxicso kill the birds
You can put them out in early April. The first sighting in Kentucky this year was March 25 in southwest Kentucky.
yes they are
Hummingbird nectar feeders, suet cake feeders, thistle sock feeders, tray feeders, and many others.
You can put them out now. Ruby-throated hummingbirds were reported in southern Ohio on March 31.
Yes, woodpeckers drink from hummingbird feeders. Red-bellied woodpeckers even pulled the plastic flowers off the feeding holes of my hummingbird feeder in order to get better access. I have also seen downy woodpeckers use hummingbird feeders.
Sugar water. They like red feeders. Google hummingbird+feeder for more.
It depends on where you live. Hummingbirds are flower feeders and consequently tend to migrate when flowers will be in bloom. So feeders should be put out in spring when flowers start blooming and should be kept out until the first frost. Its also important to change the liquid in feeders every week since it will begin to ferment.
That is normal behavior for a hummingbird. You can try making several different hummingbird feeders available so they don't have to share the same one.
They will feed when they return return from their migration. They will return in the spring as soon as the flowers bloom. Putting out a sugar water feeder should help attract them when they return.