Mics have different 'pickup' patterns, if you need sensitivity perhaps you should browse the pick up pattern, e.g. cardioid. Omnis have the lowest directional sensitivity and collect more ambient noise.
You do a DIY 'shotgun' type arrangement by placing the mic in a small can fed by straws of tubes of different lengths to optmize frequency range selectivity.
Then there are shock mounts to consider if your application is exposed to vibration
There is a yahoo groups on mics and preamps thats fairly active with all kinds of mics, custom made. Google 'Alice' microphone designs.
You mention 'product' so I suggest you do a bit of research into the subject matter as there are a lot of design options and preamp configs based on what you're trying to accomplish. We can't advise unless we know the full specs and purpose of the product. Piecemeal info requests will get you piecemeal answers.
There even maybe a way to use an LM324 opamp......(audioguru takes a deep breath now
) .........ok maybe not.