Assuming you're over-concentrated in equities, yeah. But if you're under-invested in equities, this would be a decent time to start getting more. No telling when the market will bottom out though, so as always be careful.

If you can predict that the market will go down, yes. But you cannot--that's the whole point.

You could transition more slowly to get the "dollar cost averaging" effect, but that has its own risks.

If your mix is wrong, it's best to fix it pretty quickly.