SEO for 2 companies

I need somebody that can fix all the broken plug-ins on our website and regularly improve our SEO. I need somebody with the highest Google credentials so I know they truly are connected with the latest changes in Google algorithms in order to continuously improve my SEO. I need the following:

on-page optimization
conversion rate optimization
site speed and monitoring
technical optimization
content research and strategy
off-page unique backlinks
off-page SEO optimized content

I also need help with any other aspect of website SEO that I am not mentioning above as this is unfamiliar territory for me.