I can answer some of these questions.
First, I'm using the GWS Pico BB servos. I really like them. They are reliable and light.
The 10-amp ESC should be fine with that setup. Keep in mind that if you get a 350C instead of a 300C, you'll need to use a smaller prop than the recommended 10x8 to keep from burning up the motor. The 10x8 with an 8-cell pack can pull about 10.5 amps, so be careful. I'm using a 15 amp ESC but I'm sure the 10 amp will suit you well. On the website, it says that this can support up to 12A momentary draws.
You can use LiPoly batteries if you limit yourself to 2s1p or 2s2p packs. 3 cells in series are too much juice for this motor. The ESC will work fine, however, there is one concern: the cutoff voltage is too low. This means that if you run your motor until the motor cuts out, you've discharged your pack too much and have possibly ruined it. In practice, this isn't a big deal. I rountinely get 20 min on a 2s 1500 mah pack. Until I got used to it, I landed every few minutes and checked the voltage with my multimeter to make sure that it wasn't discharging too much. When I pull the pack out after 20 min of flying, it shows about 7.4-7.5 volts. In hindsight, I wish I would have gotten an ESC for LiPoly batteries.
As far as using a brushless ESC with that receiver, I don't know, but I don't think it can be done. If you are going to go brushless at some point, you might as well go ahead and get a seperate receiver and ESC. I'm using a Berg 4*DSP and love it. It's one of the lightest I've ever seen (7 grams).
http://www.aeromicro.com/berg4.htm.
The castle creations Pixie 20 would be a great ESC to use with LiPoly cells. It's $39 at
www.allerc.com. (they are a forum advertiser, BTW.) It is light and rated at 20 amps.
Matt