already solved the "deprecated mysql" error by downloading the new file on the site.
I'm concerned about what exactly you've downloaded because you said the new file. Try to keep 1.6.3 or 1.7alpha1 but mixing them will always be more risky.
when going to http://localhost/qa for install, shows error
If you see an error about your qa_options table then you have previously installed Q2A and broke the installation.
It is extremely awkard the fact that you don't have a qa_options table. Not having that table means you have no configuration in your site and nothing at all will ever work. Finding the cause of that would be important. However, considering the fact that you've messed with core files then finding the solution to an issue that you might have generated yourself won't help others.
So let's make it simple: you don't care about any existing data in your installation but you do care about not being displayed the deprecated warning, right? Then just drop the database from phpmyadmin, workbench or whaterver tool you're using and create it again. Download the 1.7alpha1 files from the dev branch in github and proceed with the installation pointing at the new database. This is by far the easiest way to regenerate the schema.
That should be bullet proof but will, of course, tie you to an alpha (almost beta) release for a while.