This is my first year filing 1099s for a business. Can I get a laymens course in who/when you send a 1099-MISC. Is Box 7 appropriate? Do you send 1099s to legal firms for legal expenses that a business incurrs?

There are detailed IRS instructions on how to prepare and to whom to send the Forms 1099-MISC. I suggest you read them.

If the law firm is a corporation, then a Form 1099 is NOT required. Otherwise, yes, send them the Form 1099 for expenses over $600 annually.