Resolve Wordpress / Internet Explorer Compatiblity issues

I have set up a Wordpress site which is due to go live in just a few days, but appears all wrong in Internet Explorer (particularly IE9) - for example:
- font size appears about 100pt
- most content aligns to the right hand side
- some of the graphics don't display etc

Looking online, this seems to be a common problem, but the simple solutions proposed don't seem to be working... so I need someone to take a look asap and fix the problem(s) in order that the site can go live by Thursday 1st December.

I have run the site through validator.w3.org and come out with 76 errors (outlined in the attachment) - hopefully this will help.

Please bid if you have experience of resolving these issues, I am looking to hire someone who is confident of being able to fix the site within just a few days.

Full Wordpress/cPanel login details will be supplied to the winning bidder.