Hello,
I have a good bit of experience with Linux, Wordpress and updating servers. I can get you setup and running rather quickly
Regarding backup buddy, it's entirely possible this is a permissions thing. I'll do whatever I can to get this fixed, but it may be something the dev needs to take a look at.
Regarding CSS, what error specifically are you seeing
Regarding MySQL optimization, this should be done easily within an hour or so for you
Regarding your last error, this most commonly shows up when hosted on 'shared hosting', as opposed to VPS or dedicated servers. Unfortunately the only real solution for this is to move the site to a ded or VPS server, since shared hosting is always overloading themselves.
If you'll look at my profile (https://www.freelancer.com/u/twhiting9275.html), you'll see 100% positive (5 star) feedback, high completion (I don't abandon projects, but there are times employers take work and cancel to avoid paying) and a link to my own site where I've done the same for better than 10 years now. Your project will be completed with the same diligence and persistence. Your task will be completed within the advertised period of time, and be given everything needed to be done right.
I look forward to hearing from you and working with you on this project.
Tom Whiting