I've inherited an old pear tree, and it's a mess - at least I think
so.

It's got four main "trunks" which I understand is good on pear trees.
Most of the new growth has been straight up, and there is lots of
crowding on the ends of the older branches because of unchecked cross
growth. Should this new growth be trimmed like other fruit trees, or
is there something special.

Some of the oldish branches, about 2 inches thick, are intertwined,
twisted around each other. Is this a feature, or just neglect?

Lastly, is there a nice online reference for fruit tree pruning?

Cheers,
-Ed Evans