H1B extension and tourist visa


I’m right now working on H1b visa which will expire on 31st dec 2013. My husband is working in Mexico and I’m planning to go to him for good. Is it possible to file my H1b visa extension now. I’ve heard that once i file for extension i can not leave the country.Only when i get the approval I can leave… Is it that if i’ve filed extension and i’m going to mexico even when the extension result is not out, I can not come back to usa? Also, Can i come back on tourist visa here. Will I be eligible to apply for tourist visa when the H1 extension is in process.