Help needed for new Pro Tools set-up

[mikes425]

I am a 30 year voiceover studio guy looking to move from a G4 (os9 with Lynx PCI card)
to intel Imac as my main studio cpu. I've mainly used 2-track apps like bias
peak and standalone daw's in the past but want to run pro tools as my main application on
the newer mac.

Primarily the work done is simple mono voice tracking and occasional
fully-mixed radio spots and tv audio which require - typically no more than 8 channels.
(and as absolutely simple, pared-down screen display as possible...no midi, no music needs,
this is broadcast production-based usage alone... i would love an
interface that rivals the long-ago simplicity of original "Session 8" or something
rivaling Peak 2.6 with 8 channels -- but that's obviously too simple for today's
standards and another topic).

Anyway...my audio input is never more than 2 channels at a time.

Got a few questions that are holding up a buying decision re: PT.
First, for the kind of stuff i'm doing, are mbox converters good enough for pro
broadcast applications (I would be using my higher-end preamps - not those of the mbox).

Also, given my particular application, is there any major reason not
to just go with a current or previous generation USB mbox vs a
firewire (Pro or 002 ) one...If USB, how much is latency
really a factor and does the pt USB box give you some form of zero-
latency monitoring feature?

Is it fairly straightforward and glitch-free to use non-Digi software
like Bias Peak with Digi Hardware or is that cumbersome to configure and
expect to be 'rock solid.' ? I would assume with the right drivers it should
be okay but i try not to assume anything...

Finally, would there be any issues/problems running PTLE with, say a
prior generation usb mbox in the latest OSX Tiger OS? (I am at 10.4.10 and will
probably stay there for a while on the G5).

Thanks in advance for any thoughts or advice.

Mike