Brewing Foul?

I am new to beer brewing.  I just started my first batch about a week and a half ago.  I brew my own wine, so I just used my wine equipment to brew my first batch of beer.  I use a 6 gallon carboy to ferment my wine.  I brewed 5 gallons of beer and put it in my 6 gallon carboy to ferment.  However, I did not top it off to reduce the amount of air in the carboy.  I inserted an airlock as soon as I finished pouring the wort in the carboy.  Did I create a brewing foul by fermenting with the extra air in my carboy?  I plan on buying a 5 gallon carboy this weekend to keep my beer equipment separate from my wine equipment.  Should I transfer the beer to the 5 gallon carboy, or just leave it in the 6 gallon until I bottle?

Thanks,
Shannon

What you did is exactly how you brew primary only. 5-5.5 gallons of wort in a 6+ gallon carboy. Pitch yeast. Leave it there for 2-3 weeks. Rack to a bottling bucket with a boiled priming sugar solution in it. Bottle.

Don't worry about the oxygen in there. It will be purged with CO2 as soon the ferment starts.

If you control the fermentation temperature into the mid to low 60°s you should be pretty safe but should you start getting blow off you can cram a 1" plastic hose into the neck and put the other end in a bucket of water.
You can also use a thinner hose in the airlock or stopper but that runs a risk of clogging up and creating pressure (carboys aren't supposed to take pressure).

Beer yeast produces a foamy head (krausen) during fermentation. Had you topped off you would have ended up with a big mess, not to mention losing the batch.

Assuming that you're using glass, there's no logical reason to separate equipment.

I would suggest getting a 5 gallon carb to use as a secondary for your beer, and perhaps another 6 if you plan to overlap beer and wine batches.

Some people don't bother with a secondary, but I always use one. Mainly because after you leave the yeast cake behind in the primary, when siphoning off from the secondary you have less of a chance of unwanted yeast in the bottling bucket or keg.  That and I like to dry hop.

Smooth ale-ing!