They will be all right as they are, but it helps to put some drainage material in the bottom of the containers.
Maybe you could raise them up on little 'feet' aswell. That might help the compost not to get waterlogged.

They will withstand the frost, but you could, if you like, put them against a wall, or near some shrubs, for a bit of shelter, but I don't do it with mine, and they are always fine.

I agree with Hywel. They should all be fine outside. One more thing you might want to do is make a cover of wire netting for each pot , just tucked in round the rim. I have to do that in my garden because the squirrels always seem to be hunting for newly planted bulbs and I need to do it otherwise they are often dug up. When the shoots of the bulbs just begin to pop through next spring I remove the netting.

Many thanks and I will take on board your suggestions.