These are the kind of basic topics that you can easily find with a little effort on your own. Here is one link that explains microphone polar patterns.
http://www.audio-technica.com/using/mphones/guide/pattern.html

While you're on the Audio Technica website, take a look at their mics. They are great value for money and perform to a very high standard.
John Stafford

Search google for Ron Streicher, he literally "wrote the book" on all things related to mic patterns, pickup, usage, etc. Great place to start learning about it.

For a good TUBE CONDENSER mic for less money refer to NADY

NADY TCM 1050 Tube Condenser Studio Mic

http://www.nady.com/products/product_pgs/tcmmics_pg1.html

cant really comment on the nady mics but id go with an AT or a studio projects mic.....you cant go wrong with a Studio Projects B1

Studio Projects make some great mics, esp for the price. I have a pair of C4's, and they're great little mics. (For $300 you get a pair of 'em, each with an interchangeable cardioid and omni capsule, plus shock mount & carrying case. Sweet.) They really sound nice on a variety of things.

AT is a great line of mics as well, I just picked up a pair of 4049 omnis, in addition to a bunch of other 4000 series mics I already have.