Personally I think the Universe is a shape we can’t comprehend. Its contained but has no outside. Its expanding but not away from a certain point. Its completely infinate. Trying to imagine it is like trying to think of a new color (that isn’t a mix of any other the other colors). You just can’t do it.
Yes, but it would still be impossible to determine the centre because wherever you stood, everything would be moving away from where you are and you would seem to be in the centre.