There are tweet ads, yes. They are usually marked as "promoted"
I found it useful to "report as spam" the account they were coming from so at least you only see them once...
I found the new layout to be headache inducing for my english-speaking, left-to right-reading brain so I switched to the Chrome plug-in Silverbird on TVGugs recommendation... and haven't seen the promoted tweets since. Maybe that's because I'm using lists more... but it solved a lot of problems for me.
Uh, not sure what you mean. You have to burn the ISO file to a blank DVD, then do an install on a clean hard drive. The beta won't allow you to upgrade. You could use VMware I suppose but that's if you have it already. I just did a clean install.