Fixing bugs and enhancement to existing custom php custom blogging website

I have an existing website that is 90% complete but still has many outstanding bugs and needs some enhancements made to certain areas to take it from test to live. The site is written in custom php, no framework used. It uses MYSQL. It has some Ajax scripts that pull data from database. It uses Responsive for mobile. High Level requirements that need to be met 1) The blogging submit page where users submit articles currently works but requires improvements. 1 - a) A user can submit a URL and the URL will automatically grab images to use in the post, they can tag the post etc. I require the image grab function on this form to be improved, have images scale correctly and grab from different img codes on different sites. 1 -b) I have created a list of tags that I want to assign to post category so that when user choose a category the tags will be selected from database to show them. This will create better control over the tagging. 1-c) General bug fixes around robustness of the submit form 2) General site bugs. 2 - a) The login page uses bootstrap and currently no failed login info appears if user enters incorrect username 2 - b) Want to investigate options to integrate login with Facebook and Google +, Want someone with experience who can integrate API for this. 2 - c) General formatting of layouts from front page views, to profile page views, to post views. 3) Design 3 -a ) The site uses Responsive and works quite well on mobile. Dev team needs to be experienced with Responsive., 4) Optimise, and harden the code to be 100% secure and efficient. I have a complete list that I can provide to developers so that can accurately quote. I require the work to be completed ASAP, so I am happy for a team to work on the site if required. I also require competent dev team that have proven experience and are 100% committed to completing for me - I don't want a dev that has 5 projects and I am just part of a group that only gets a small part of their total time. I need a dev team that can focus and get my site live!