Okay, thanks iCake.

If I wanted so say 'the hand swelled up to the size of a baseball glove', I'd be inclined to say 'рука распухла с бейсбольную перчатку'; c + accusative. Just in this one sense of meaning 'the size of'. And then maybe I'd use около for everything else, except for approximations of time, where I tend to feel like using noun followed by time; 'час три' etc. I seem to recall seeing примерно used in a technical/engineering context, but I may be misremembering, and приблизительно to me means 'in the region of', which is just another expression for approximately, which can be used anywhere you like.

Does that make sense? Or is some/all of that wrong?

One last thing, how do I 'like' a post? I'm sure I used to know how to do that...