amount of beer in secondary

i have a american hefe. i want to bottle 12 bottles regular, then take the rest and secondary with raspberries. does the extra headspace on my secondary matter?

2nd question: i wasn't planning on making this a fruit beer, already been in primary 3 weeks. with the add'l 10 days in secondary be cool?

thanks

An extra few weeks in a secondary is usually good for a beer - critical for some of the higher-strength brews, so an additional 10 days in a secondary would definitely bring out more of the flavor of the beer itself, in addition to flavoring with fruit. The extra headspace will probably not matter too much, I secondary in plastic jugs and I always have a good 4-5 inches of extra room, and my beers have all turned out pretty well.

The thing to be careful of there is the priming sugar. Normally you'd get your priming sugar ready and dump it into the whole thing, but that will re-start the fermentation in your secondary and change the flavor, which I'm not sure you want.

I'd defer to one of the more experienced brewers on this to give either the per-bottle amount of priming sugar (which is done less because it can lead to over-carbonation), or the full 12-bottle volume (12oz bottles? or bigger?) being put into a temporary bucket, adding the proper amount of priming sugar for that volume to that temporary container.

1) Assuming you are going to use a 5 gal carboy as a secondary, the headspace really shouldn't be an issue, especially if you are adding more stuff into the secondary witht the beer. 12 beers is only about 1.25 gals.

2) The extra 10 days in the secondary isn't going to have any impact on the beer.

i was going to take out a 12 pack, use the 1/4 of priming sugar, and bottle.

take the remaining wort and place in 5 gallon secondary over 2 pounds frozen rasberries and 1 pound mixed berries.