Hi,
Firstly welcome to Freelancer, hope it works out well for you. I have hired a few people through here and it is wonderful if you get the right person.
I use a Condenser mic with a large Diaphragm for the best audio recording. Basically I'm a bit of a perfectionist, I want to make sure that I get it right every time. As while you may be using the recording - its my name and vocals attached to it. The most important thing is that you are happy and love the end product.
I hope you are ok with it but I prefer to have a number of milestones, as it ensures you get the product delivered and that you're getting what you want when you want it, also it means as items get completed you can release a milestone, that way I can eat and you can get your product done the way you want. Like having a real employee.