First of all, you are speaking about your experience (no matter whether the action is completed or not) and you do not indicate the time of the action. Therefore, you should use Present Perfect (though, in AmericanEnglish Past Simple is also possible in this situation). Then, your word order is not correct. If you have two adverbial modifiers, for example, one of time and another of place, first you should say WHERE and only after that WHEN. I have worked in different restaurants for a long time.

if you are still working in different restaurants you must say in Perfect: "Yes, I have worked for a long time in different restaurants" if you do not work in different restaurants anymore you may say: Yes, I worked in different restaurants for a long time.

Your CORRECT! either answer works ^.^