You can ride the Total Rewards shuttle between the four Total Rewards properties (Showboat, Harrah's, Caesar's and Bally's) if you have a Diamond card or a room key. But, the shuttle doesn't run very often and usually there is a line to use it. I would just hop on a jitney for $2.25. It's more convenient.
I think it's 25 or 50 points at the Showboat for free parking. It may be the same at Harrah's. If you park indoors at the Showboat you pay on the way in, so you have to print out the voucher after earning the points and get reimbursed with your parking receipt at the cashier. You can get around this by parking in the outdoor parking lot at the Showboat where you pay on the way out.
It's easier and shorter to walk to the Golden Nugget from Harrah's. It's fairly well marked. To walk to the Borgata, you walk along the water in the opposite directon of the Golden Nugget. There is a concrete path between the props but it's a little difficult to find. If you really want to do it, you can find someone at either prop to help you find it. It takes about 20 minutes of brisk walking.
There are only three 25c/50c/$ 9/6 JOB machines at Harrah's. They are in a carousel of 3, at the end of the main hallway, sort of next to the Xhibition Bar. There is $ JOB in the Diamond Cove.
There are eight 9/6 machines at SB, 25c/50c/$. They are in 2 blocks of 4 and I think they are labeled on top as KL and KM, or something like that.
You will probably be able to earn two free buffets for a few hours of table play at either the Borgata or Harrah's but you may want to play at Harrah's because you can use your comps at TR props nationally. Both props will treat you pretty well if you log some time at the tables, especially if you haven't been there before, but if you aren't planning on making a trip back to AC soon, you won't be able to take advantage of any offers you generate.
The room tax for your comped room at Harrah's is going to be $13 a night.
In PA, Harrah's Chester is about 20 minutes south of the Philly airport. Sugar House is about 20 minutes north of center city Phila. Parx is like a half hour north of center city Phila. I believe. No PA prop has full pay video poker though.
This is all the info I have off the top of my head but I'll try to answer any further questions if you have them.