Wordpress - edit image, remove \'site built by\' code

There are two parts of this job: 1 - I am looking for someone to replace an image on my Wordpress website that can be found in four places: home page (transitional photo), and three content pages (static photo). I have a screenshot attached with the photo I would like to have replaced with another photo. I'm not sure if these photos are all linked to the same source or if each needs to be changed individually. I would like to keep the current shading behind the photo as it matches the site's colors and looks good. I will provide the replacement photo (two options for simplicity) as well. This is probably a fairly quick and simple job. 2 - I am looking to have the code removed showing 'web design by .....'. I have attempted to find this code and remove it, but have not been able to find it in the coding. I know it is not good for SEO and general marketing to have it there, so I would like it removed. Since I have not been able to locate it for it to be removed, if you want to price each part of the project separately in case you are unable to find and remove this code, please do. Any questions, please let me know. Thank you.