You need the HTML meta tag to control cache in the webbrowser. However, all browsers caches images in their 'temporary internet files' (or something similar) folder. Moreover, you should rather optimize the size of the actual photos. You can create nice quality web friendly photos, little over 200KB. And you really shouldn't worry about SEO. Your page would have to load really slow, and this for quite some time, before it would affect any SEO ranking ;-)
I don't know why you think you need .htaccess to accomplish caching in the web browser.
PS: A forum is for free advice. If you want to pay somebody, you need to go to freelancer.com (or something similar ;-) )