There was no distinction between V and U when W first started being used. They were considered the same letter, with V just being the style for writing it at the start of words (like that long S that looks like an f). So you would write “have” as haue and “upon” as vpon.
When it was representing a consonant in classical Latin, it sounded like a modern English W. So the famous veni vidi vici - I came, I saw, I conquered - was pronounced more like wenee weedee weekee.
Eventually the V sound started to emerge in some places where Latin and its descendants had used that W sound before, and people started treating the two forms as different letters. By this point the W was already in widespread use, though, so whatever people already called it had a good chance of sticking
They would, but they also did. They were herbivores
To be clear I do not actually think that they were as stocky as that pic. Point is that for land animals, though, eating plants actually is often the way to being huge