No, I'm using Whidbey for 32-bit builds. There aren't enough developers with Athlon 64s yet.
I find 1.0 pretty stable though I avoid multimedia in the browser. I generally download a file and use a player locally.
I haven't seen any problems using embedded Acrobat though there is an interesting hack that improves Acrobat performance at startup.
For me, getting a 32-bit build with Whidbey was a big accomplishment as I have been trying for a few months on and off. It turned out to be incompatible libraries (I had an older MSDN version whereas the public libraries were from a later Express version).
I haven't checked on the 64-bit progress but probably will this month.
The FireFox team consists of four people and at least one of them has been spending a lot of time on marketing. The Mozilla team behind Firefix is a lot larger though.