Can I make my title an image

Yes but you will have to purchase an annually renewable custom design upgrade http://en.support.wordpress.com/custom-design/ and do the required CSS editing http://en.support.wordpress.com/custom-design/editing-css/ to accomplish that.

would that affect search engines on google for example?

Yes. The Google crawler cannot read image scripts and therefore using the Alternate text ALT attribute (providing a concise text description) will allow you to tell the crawler what the image is referring to. If you want your images to be indexed then give your images the full treatment. http://onecoolsitebloggingtips.com/2012/01/08/get-the-most-out-of-image-search/

if i change url, would this affect followers?

If you do not purchase a site redirect upgrade http://en.support.wordpress.com/offsite-redirect/ after changing a URL then all the original links to your content will be broken.
http://en.support.wordpress.com/changing-blog-address/

3- Can I make my title an image and would that affect search engines on google for example?
4- if i change url, would this affect followers?

Thanks,
Suzan

Can I save this sort of editing I do to one theme to be applied to future themes?

No. Each themes is different and has different features and settings.

Yes. Create a custom menu and add a custom link.

2- Can I make one of the pages in my blog open a new link outside wordpress or my other blog on WP?

Thanks,
Suzan
Blog url: http://mideastcan.wordpress.com/