I have a WordPress site with a Permalink of /%category%/%postname% of over 350 blog posts and I want to change it to just postname /%postname%

I have a few questions.

Is there any quick way to do the redirects? So say I have a category of "fruits" could I put something in the htaccess that would redirect all posts that were originally site.com/fruits/postname to site.com/postname?

And, secondly, it is bad to have too many redirects in an htaccess file? Would 350 slow down the site?