How to get the height of the entry? Use:
"entry bounds height"
How to enable scrollbars?
To answer this, I'll first point out that the way you're getting the EntryView's displayed isn't really the best way. You want to create a custom control like I explained in your other question How to create a window in smalltalk. You can use a CompositeView for the view and add each of the EntryViews into the composite using add:at:.
Once you have that, you can go to the Details tab in the UIPainter property editor of the view and turn on Vertical scroll bars.