You can ask the lawyer to write the letter first. Generally the lawyer got to be paid first before starting doing things. It may cost 100-300 dollars :(
If later on you company agrees to pay for the legal fee to the lawyer you found, they will pay for the other expenses. If they insist using their lawyer, it is OK with you because once their lawyer really starts the case, he will be clear on what to do.
Most small business does not pay for the leagal fee, it is possible that you may have to pay by yourself. Then it does not matter to the employer whom you use.