wandless magic

[heidi]

No: HPFGUIDX 3296

Does a flame freezing charm need a wand?
Hopefully not, because then a witch or wizard caught by witch-hunters without a wand won't be able to perform the charm and enjoy that sought after tickling sensation and
basically would be burned to a crisp.
If a flame freezing charm needs no wand, what other spells don't, either?

Can one "accio" without a wand, if one is trying to "accio" one's own wand?