I was wondering if anyone had any experience playing guitar in a Pit Orchestra.
I have a couple of questions.

My part is mostly strummed chords throughout each song in the musical. The chords are easy to play but how do I know what variation of the chords to play?
The only annotation is the chord name (ex. F9) and the rhythm.

Secondly, the guitar book is combined with the mandolin book. I may be asked to play the mandolin parts as well which would require actual reading. I can read notes in treble clef (I play the violin as well) but I've never read sheet music for guitar before.
How do I know where to play the notes written on the guitar?
Any other tips on reading guitar music would be appreciated.

Thank you.
in pit orchestra (i'm assuming for a musical) books they always annotate where to switch instruments and will notate it appropriately
concerning the chord voicing, you want to just play what you would play in any other song
and the rhythms go along with the song type (probably mostly swing)
for example swing songs most have a straight 4 beat staccato strumming pattern or on 2 and 4
the director will always guide you along if you play anything wrong
Lastly for reading, you'll just have to sit down and find the hand position most convient. for example if you have to play a combination of notes such as C#, F#, D#, etc. you want to move your hand to the position in which moving around the neck is need the least... think of using the 6th fret on the G string for a C# and the 9th fret on the A string for an F# rather than the normal frets in between 0-5