For recording, you need to Mic a piano from a decent distance - otherwise it will not sound natural. Open the lid, and mic from about 3-8 feet away from the opening - I would use two omni-condenser mics spaced evenly apart. It is different compared to when you are micing for re-enforcement (ie mics within the piano on the sound board) - as the re-enforced sound is not true piano... Have a play, and you will probably see what I mean.
For the choir, cardioid or super-cardioid pattern condenser mics - if possible, I would use hanging choir mics - 200 piece choir, you would probably want 6 - and I would separate the mics based on the sections the choir is divided into.
As with all recordings, you will want to deaden the space - don't fall for the "We are a choir, our sound requires the spaces reverberation" line - keep the space dead and add the reverb post-record - that means you will need to provide monitor mixes - again, provide a mix for each choral section, one for keys and one for the conductor.