Dan
1. Please update your sign-on to include your last name. It's one of the rules on this forum.
2. The best way to mic most orchestral instruments such as a flute would be a miniature mic that clips on to the instrument, such as the
Audio-Technica Pro35. This is investment pays dividends in terms of convenience over the years.
You could position a condenser handheld mic on a boom stand near the flute, but it's always a good idea to eliminate mic stands for a number of practical reasons (additional stage clutter, etc.) .
Shure has a number of good reference publications that are helpful in mic selection and technique, such as
Microphone Techniques for Live Sound Reinforcement.
3. Regarding your second question if the foldback (monitors) should be the same volume as the house, the answer is "no". Foldback monitors should be the minimum you can get by with, but loud enough that musician or vocalist can adequately hear themselves and others. Excessively loud monitors reflect sound back in the house (and choir mics); when the reflected sound mixes with the house sound, the result is a "muddying" of the sound quality. The front-of-house (F.O.H.) console operator then feels compelled to increase gain to overcome the mix of monitor and house in a domino effect, often resulting in ridiculous sound pressure levels in the house.