Newbie having display and text re-sizing problems

A series of questions? I was an iWeb user so am at a basic level only.

Why doesn’t the v button display the finished layout? I keep having to use alt cmd B to view it as it actually is. For example if I am using black writing on a white box on a picture background I don’t see the white box using V which means the text may be illegible.

If I open a text box under D, say a heading, I can align the text horizontally to be left or centre justified but I can’t align it vertically and it is never vertically centred, this looks unprofessional on the finished site.

If I add an element to a page it may (or may not) subsequently change the text size of all of the writing on that page making small text huge and titles small… but you only find this out when you view it on a website, on the design and V settings it looks fine. This is really winding me up, maybe I have a setting wrong somewhere. I have checked to make sure that settings are the same on different pages but when I ftp it the pages you have tweaked are all wrong.

Any suggestions gratefully received.