Hello
My name is Eva, I would like to work with you.
Here are my suggestions:
Before you even start considering to work with anybody (including me) make sure you have a solid backup. This way you can be sure that the site is recoverable, if something goes wrong.
I start the work with creating a backup anyway, but with backups it's never to many. After this I create a "development server" where I first get to know the site, and make the required modifications and test them. If everything works smoothly than apply them to the live site.
I can correct the issues you mention, and also see what can be optimized for the site to load faster.
After the initial job, I suggest to create a hourly project (of course if you are happy with the work) and continue monitoring the site for errors in webmaster tools, or other small issues that have to be corrected. Please remember that there is no PERFECT website, a website is a "live thing" that constantly changes and errors can emerge or happen over the time.
Looking forward to hear from you
Regards
Eva