I've started out my first UX project. I would like to know in which cases sellers might want to have a sticky bar with CTA buttons on it (see example below). How can I know that? Should I create a survey? Thank you ahead.
The development cost of adding those buttons, now a days, is very cheap so I would implement them and measure if generated the results you wanted. If not, think of an alternative. If you are going to ask the user about this, take advantage of asking something more than just if buttons with more "call-to-action" effect are necessary. That's the kind of conclusions you get by measure user performance, not asking them.
It can work, not in every circumstance. In this case I think a separate page with Contact + Localization will be helpful. However this option will allow fast availability to specific elements in the interface.
There are a lot of patterns to create a decision point for user to interact with your site. The most popular for now is which communicates with a user in real time. For example integrating chat system (for example LiveChat)
Of course survey, always be a valuable solution.