It should grow as pussy willow grows quite fast. I once planted a stem from a few I'd picked and after a few weeks found they had all rooted in the vase.

No, the main trunk will not get taller - I'm assuming you're talking about a Kilmarnock willow (google to make sure). As you've seen, they're grafted at the top of a straight stem or trunk off a rootstock - but that trunk only gets wider, it stays the height it is when you buy it, so if you think its too short, don't get it, get a taller one. That said, over many years, they can occasionally get quite tall, with some growth of the main stem - but it takes years and years, so to all intents and purposes, how it looks now is how tall it will be for 10 years or more - but it will get much wider.

Maybe she could have one delivered?

Thanks for your replies, I rather doubted that they would grow really.

The main stem won't grow any taller, but the weeping branches will gradually build up, layer after layer, as they arch over.

Triffidkiller - you have posted the same rude comment on another thread. Why has Bamboo ( who is female) bugged you so much?