Urgent Website Fix & Optimize

My client’s site is live but stumbling: several pages throw 404s, key buttons lead nowhere, overall load time drags, and sporadic server-side error messages are spooking visitors. There is even a small “assist-bot” feature that now crashes the minute it is invoked... (Budget: $30 - $250 USD, Jobs: Debugging, HTML, JavaScript, PHP, Web Design, Web Development, Website Optimization, WordPress)