Just to add detail: the park is 640 acres! There are many areas of the park.

All activities are over at 10 pm.

The Kelly is open, however there is a race on MLK so traffic could be worse than ussual.

I do not know the street numbers, but if you ask to go to "Boat House Row", that is the start of the Park.

There are a few obvious spots along the river

Actually, there is a stone tunnel near that bridge that is way less than 135 feet. Even this tunnel is capable of a truck passing through.

t Suburban Station at 15th & JFK Blvd. or at 30th Street Station, which is closest to Kelly Drive. There are Flash tour vans (purple) that have many stops around the city. Center City Philly is very walkable -- about 4 miles square. There are those rentable blue bike stands all around the city -- you register your credit card at a kiosk, or online, and pay about $4/hour picking up and dropping off wherever is convenient. (There's an app to show you were the stands are around town. I haven't used that yet.) Also Wheel Deals you can rent not just conventional bikes, but surreys (sizes for 2 or 4 people) or lower to the ground peddle go-karts for 2. (they have a few covered ones but the sun is not so insane nowadays). There is a groupon deal for those rentals at 1/2 off -- just pull it up on your phone in the groupon app or at the groupon website. (Check ahead to be sure the offer is still on there.) There is a cafe' also for beverages along the Drive, but there are far better places to eat all over the city. Wherever you are, call up Yelp or Trip Advisor, plus in your intersection or use location, and many will come up. Closest to Kelly Dr might be Fairmount Ave where there are several between 25th and 15th. Or alone 1800-2000 blocks of Callowhill. (Great taco place (bargain, great quality), Sabrina's (gourmet diner type fare), Zorba's greek,... Many more. Wear sunblock or hat! Even though temps have dropped, sun is still intense. Also Art Museum is at top of Kelly Drive, so you can pop into their cafe' and peer at some art. Great African design exhibit at Perlman Center, across from museum, where you can pay lesser admission for just that show. I think free Sundays-- pay what you will.

It's a tough question. You can park behind the Philly Art Museum and look for a nice spot for a picnic. During the week it's fine on weekend it's very busy all over

Parking is not easy on the Kelly Drive; there are several pull over areas along the drive and parking at the Philadelphia Art Museum; however, if you go on Martin Luther Drive (it's the road that runs parallel to Kelly on the other side of the river), there is lots of parking. And some picnic benches. You'll have to find which parking area has a lovely view of the river; it's not as constant as Kelly Drive is. Enjoy!