Wordpress Optimization and Custimization

I have recently converted a Joomla website to Wordpress. I need the following things done. #1. Wordpress Optimization; currently the website is receiving very poor scores in Gtmetrix, My Pingdom tools, and Google website speed. Additionally, the website is operating slowly and at times it loses connection with the database. Unless the score in all of these SEO websites improve, the project will not be considered complete. #2. I need for users to be able to create an account, login, edit profile, reset password, remind password, post articles, etc. (like you can do from a Joomla website), all from the front end. Administrators must be the only ones to access the Dashboard. #3. The website is for Spanish speaking audience; therefore, the front end must be in Spanish, while the backend remains in English. #4. In Joomla the size of the website was only approximately 30 megs, when I do a backup of the website now with Akeeba backup, the size of the website is over 180 megs. Something appears to be very wrong with this, It is my understanding that all if not most of these things are done with plugins; however, since I am new with Wordpress I don’t know which ones to install and hoe to configure them. All work performed on the website must be done via Teamviewer, NO exceptions. Please don’t bother to waste your time or mine if you are unwilling to accept these terms. Thank you.