I would like to know, if I want to design a survey with two different parts, one part that I need to set the time limits and the other part is fine with however long it takes for people. Can I do that?
The way to limit a respondent’s time is an action called Page Timer. The page timer can be set to limit time for either one page or the whole survey.
Your need only gets complex if you want to give a single time value for finishing several pages but not all pages.
One way to do something like that, is to actually create the survey as two surveys. One survey would be timed and the other not timed. Whichever one is first could redirect to the second part using the Redirect to a URL option on the thank you page. It would seem like a single survey to the user and you could pass the Session ID as a field value to the second survey to link the data.