Bill,
The table design is genius. It's a simple, plastic, folding banquet table. I'm guessing 48" x 24". The Curved, top part is plywood, and is mounted on wooden blocks that are bolted to the table top. The entire inside is empty, with a cutout for wires to drop through. The sides are just cloth. I think it's a kind of canvas. It's simply stapled the to edge of the Top, and drapes down to make the appearance of a piano shell. With legs folded, I can carry both at once; one under each arm.
(not MY legs, of course ... lol)
If there's a down side to the lightness, it's that people still seem to think they are more sturdy, and sometimes try to jump up on them. (Crazy people) Movies, like "The Fabulous Baker Boys" glorified a performer on top of the piano. Sheesh. So, we're always aware when someone gets too close for comfort.

We've both got iPads on the job, and a few times a night we have to look up a lyric that we need, but 90% of the routine, is just that ... routine. The key is to look like we know what we're doing - fake it 'till you make it mentality. The performer taking the lead usually gets most of the attention, so the other guy can search for something relatively unnoticed.

Some major crowd pleasers include:
Most Beatles esp. I Saw her standing there, and O Bla Di, O Bla Da
Most Billy Joel esp. Piano Man, and Italian Restaurant
Most Elton John esp. Benny and the Jets, and Crocodile Rock
Johnny B Goode
Build Me Up Buttercup
Jack and Diane
The Joker
Whats Up ( heeeeyyy, eyyyy, eeeyyyy)
Brown Eyed Girl
Maragaritaville (This lets Capt. Russ out!)
Sweet Caroline
sooooooo many more...

Pick songs with a universal hook, or simple chorus that they crowd can sing easily. The show is really ALL OF THEM, and no one in particular. It's very different from Karaoke, where singers are ego driven, and spotlighted. This is a party - plain and simple. The crowd is unified in song. It's really fun when it's the whole room singing along. The dueling aspect helps keep the energy up, but this type of sing a long can absolutely be done my a single performer. It's just harder on your chops, and less fun to watch because the banter is missing. There's LOADS of comedy and interaction between performers, as well as the connection to the crowd. Doing it alone is VERY tiring, and you can loose the crowd easily when you make all the decisions yourself.

As far as I know, this routine started in Baltimore (or New Orleans, maybe?) and was built on a concept called "Little Ditties" back in the 80s where you never got to finish a song. The people would tip to hear a song, and someone could tip 1 dollar more to STOP the song. We once got over $70 to finish Sweet Caroline. Funny stuff.