Newbie with some questions!

Hey everyone, I just recently purchased a 2010 Toyota Tacoma and I'm planning on installing my first aftermarket stereo system (well, I'm buying the gear myself and then hiring someone to install my stuff).

I've got a bunch of questions, but here are a few specific ones:

1.) Any opinions on the Alpine SPX-13PRO speakers?

2.) If I go with the Alpine SPX-13PROs, they're 80 watts RMS per speaker. I've already got an Alpine MRV-F450 5 Channel amp, that does 4x50 Watts. Do I need to bridge the 4 channels to two in order to generate the 80 watts I need for the SPX-PROs, or is 50 watts enough to power them and still sound good?

3.) If I have to bridge my amp for the speakers I've heard that I'll lose true stereo sound (ie. won't be able to alter the volume left to right on the speakers). It'll be mono, essentially. I've also heard that I can potentially bridge my speakers as REAR and FRONT on the amp, but they'll function as "right" and "left" for the speakers-- ie. maintaining true stereo sound. How is this done and are there any disadvantages to doing this?

Thanks for your time!