Hi There Superior,
Here is my take on Google PPC and my answers to your questions:
1. Yes it is worth it - IF you have a good website that it at the other end of the click. If not, don't waste your money.
2. It is a learning curve. You have very limited characters in your ad to get your message across and a potentially huge audience you are talking to. You can spend a lot of money while you are learning what works and getting useless leads. My advice. Hire a professional marketing expert (that understands your business well) to do this for you. What you will spend in their costs you will save in bad leads and more importantly, wasted time. Don't also forget that your ad needs go to a landing page that is designed to convert into leads. Again something I would work with a pro to do.
3. Almost 100% residential.
4. Depends completely on your location and demographics. If you are in a very competitive area your leads will cost more. Also when calculating your cost per lead, you need to average your unconverted click throughs, telephone call leads that originated from an ad as well as any leads through your online requests for estimates, etc.
We launched our website in January. I pay my web/marketing firm to do my SEO and my PPC campaign. Looking back, I would skip the money I have spent on SEO (other than properly setting up a website for it) and spend the money on PPC and traditional advertising. If you are in a highly competitive area like I am, SEO is a long process with no guarantees of success. The energy and money I have spent on trying to get on the first page of google seems like a complete waste of money considering I can simply PAY to be there and I think few consumers care anymore if they are clicking a google ad or an organic search result.
I am no expert on any of this so I can only tell you from what I have learned in the short time I have been doing this. There are some pretty knowledgable guys on this forum that can certainly give you very specific and good advice but if you are at all busy with your business, running an PPC campaign with a hit or miss attitude can be both time consuming and money sucking.