I was able to hear some of the traffic using my Baofeng F8HP with a stock rubber ducky antenna, so you don't need much on the receive side. At least when the ISS is close to you. Not sure what the window is as far as how far removed it can be from directly overhead, and yet still be able to receive that signal with a small antenna like that.

What it takes to hit the repeater I'm less sure. I've heard it can be done with an HT like mine, but I'm guessing that's only possible when it's directly overhead, or very near so. That said, I'd be happy to find out that I'm wrong about that.

I believe you can hit it with an HT, although the Youtube videos I've seen of doing it have been an HT with a hand-held Yagi cabled in in place of the usual whip antenna. A resonant dipole would probably pick it up - as others have said, the signal's fairly powerful.

Satellite comms is something I want to play with, personally, so I welcome this news. Need to get my Foundation license (UK) before I can go two-way, though.

Yes I've received it on a portable even. For a satellite it's easy probably because they're so close (LEO) and have plenty of power too burn.

For listening, a QFH antenna is ideal for LEO objects. It's typically made of copper pipe or the braid of stiff coax.

Definitely can pick it up with a HT, just caught it for ~3 minutes in the Bay Area on a Baofeng HT with whip antenna, and even picked up the first part while I was still indoors. There was a lot of static although I could make out some of the sentences.

Absolutely you will do well with a dipole.