If you are going to split part of the site off,  the auto makes the most sense since it is local.  Usually local is much easier to rank for than national, but that depends upon the competition in your geographic and product areas.

I have ampersands in lots of title tags... have not seen any problems.

Lots of people have ampersands as part of their brand

http://www.google.com/search?aq=f&sourceid=chrome&ie=UTF-8&q=%26

I agree with Robert.  Focus on keywords.

I don't sell "services" but I do sell "products" and for the products that pull in a lot of money I have a product page and an article page.  The article page describes how to use it, how to fix it, how to save money with it, etc.  Both of those pages pull in traffic but the article page is the one that attracts links, likes, etc.

I think that the decision to use a search bar depends upon the size of your site and the type of information / products that you offer.

I have a small retail site (under 100 pages) and nobody used the search box even though I had it big and obvious in the upper right corner of the design.  When I say "nobody" that is not an exaggeration.  NOBODY.  I removed the search box.

I have a large information site (thousands of pages) that has a well-used search box at the top right of every page.  This is a google search box and adsense displays on the search results page.      Here is some data....

* Site-wide about 4% of the people who arrive at the site use the search.

* About 6% of the people who view the homepage use search.

* About 4% of my Adsense revenue comes from the search page.

* Using CrazyEgg's "Time to Click" feature I can tell that a lot of people who use search on our homepage  immediately click the search box - in under five seconds.  This suggests that these people are using the search box to navigate the site.

* The most valuable thing about the search box is the query data.  I use Clicky analytics and it captures the query strings. If I look at them I see lots of people searching for topics that I do not have on my site and topics that I do not address with a dedicated page (hundreds of searches per month for some queries - this is on a site that gets 100K  visitor per day and has thousands of content pages).  I am using this query data to inform content development.  Very valuable.

* In addition to the search box at the top of every page, we also have a second search box that appears at the bottom of every article.  It is used by about 1% of visitors.  When they finish reading an article the search for something.

So, although I removed search from the small retail site I am keeping it on the information site because it is used by some visitors to navigate, I find the query data to be valuable and we derive 4% of our ad revenue from search.

Finally... if somebody is on my site.  I don't want them leaving to search somewhere else.  I want them to use my site search where the content of MY site is the only thing that they will see in the search results.