I keep getting air bubbles in my icing. I add a little cream cheese to a basic buttercream recipe. Would whipping the cream cheese put the air bubbles in it?

yes it will. Beat it low and slow. Once you hot knife it, you shouldn't see the holes anymore.

That has happened to me once when I had used the mixer too long on the icing. I used a hot spatula to smooth out after I iced the cake.

Great -- thanks. I'm trying a basket weave, so it's not possible to smooth out the bubbles. I'll try mixing slower.

Sometimes I put the icing in a large bowl and kind of ice the sides with a knife. Especially if it going into a bag to decorate with.

I just recently made a double batch of icing and I noticed that I had a lot more bubbles in the double batch compared to the single ones. I think that you just have to mix it longer and then it doesn't turn out nearly as nice.
Cali4dawn gave the hint once that you need to mix your butter, crisco, and flavoring for like 5 minutes before adding the sugar. When that stuff is at room temp and you beat it for that long it comes turns out so smoothe. Than you add the sugar and any extra liquid you need and beat at lowest speed for the shortest amount of time necessary.