First and foremost, you have 45 page validation errors. You can see them
here.
Regarding your questions:
1. Yes, the purpose of the site/business is most definitely clear from viewing just the homepage.
2. Yes. Your navigation is set up well and it is easy to access the different parts of your site without getting lost.
3. Yes. The design you've chosen works well for your site, and the layout/design does not get in the way of the site's purpose; the design does not distract me from the content.
4. Yes. If I were looking for such a service and came across your site, professionalism and trustworthiness would not be an issue. My first two instincts would be to check a) examples of your work, and b) a comparison of your prices.
Now a few things you may improve upon:
Your "Gift Certificates Now Available" button does not fit in with the rest of your site. I understand that you want it to stand out, but I think the boxy design doesn't fit in. Either that, or the color. I can't quite put my finger on it.
I'm not sure if this was intentional or not, but your background image repeats unexpectedly about halfway down the page. It doesn't seem to happen on your home page but does so on other pages. This looks disorganized and unnatural. An easy fix in CSS would by to specify the background image to not repeat:
background-repeat: no-repeat;
The links you have at the bottom of each page would look better centered, in my opinion.
When I click on "site map" in the upper right, it takes me to a page that looks almost identical to your home page.
Overall, I think the site is very well done and does a great job of presenting your content in a very elegant and consistent manner. Nicely done.
The Beer Monocle. Classy.