google adwords, yahoo, ppc manager

Project Description:
I run a small water filtration equipment company (please ask for website name). We've been around for about 3 years and need a PPC manager.

We just don't have the time to manage it ourselves right now because we are in the process of remodeling our whole site and for us it is a priority to get this up before July.

There are only a few products we wanted to focus on at the moment and we hope that someone can really increase our ROI for those products.

This is my first time opening a project like this so I have a few questions:

1) Do you think you can guarantee a positive ROI? (I realize it's almost impossible to ask but I thought I'd give it a try). Is there an ROI you can give me?

2) How long do you think it will take before I will start seeing results?

3) What is my monthly PPC cost for getting the good results?

Please contact me asap.

Thanks in advance.
Tai