In small amounts 5-10% the answer has to be not a lot. It's usually used to aid in head retention at a rate of 5% of the grist. In larger amounts it's hard to describe in a beer, well...to me anyway. Have you tried Titanic Brewery Iceberg Get a bottle...you won't regret it :drink:
Though I'd be interested in hearing someone else's thoughts on it, I've used Crystal Wheat in a stout, the stout is good but I can't tell personally what makes it taste good. :)
No. Have you tried a wheat beer, definately no nut or toast in them.
Toast is usually from roasted malt, as for nut I have no idea sorry.
EDIT, looking through various recipe books nutty flavour seems to come from a combination of roast and crystal malts. Rye is also supposed to give a roasty flavour.
Have a look here
Thanks for the info i'm looking to make a scottish stout I hav'nt got a recipie but was reliably informed the main ingredients are pale malt, chocolate malt, roast barley and wheat malt and it had a toast slightly nut flavour and I was wondering if it was the wheat that gave it the flavour as i've never used it but looking at the link you gave it might be chocolate roast wheat malt :hmm: