I played that show a few years back, and we're starting rehearsals for another production it in a few days. Get a OCR (original cast recording) there are 2 one from 2002 and one from 2013. Get the 2002 one. In the '13 version the song "Summer in Ohio" is in B major, the '02 recording has the same song, but in Bb, and that's what you'll see in the rental music. In song #5 "Moving to Fast" there is at the top of page 5 about 16 bars of chords for piano, bass and guitar. It's totally open solo. On the '02 recording the piano fills the whole section, in the '13 recording that section is omitted, so you'll not be able to see what happens. Apparently in the current production I'm involved with we'll pass the solos around the rhythm section.
Jason Robert Brown, the composer, learned about bass by listening to Jaco recordings and so this piece and many of his other shows are written with fretless electric in mind. The first time I played the show, I did it on fretted and there really isn't a problem there, but for this next production, the music director has asked for fretless. It's a challenge. Don't try to walk into the first rehearsal unprepared. If they are using the prescribe orchestration you'll see piano and guitar one violin and 2 cello. This is not easy music for anyone in the pit. Good luck, it's very rewarding music.
BTW, the only song in the show that is just R-3-5 walking is "Summer In Ohio" and most of that is written out. Harmonies are not simple or standard progressions. Expect a lot of chromatic shifts with flat 5's in the chord.