Hey there, first of all.. I'm quiet a newbie into pro recording so forgive any ignorances. Heres the story.

I own a zoom HD 16 track recorder
line 6 x3 live
pc running ableton.
NT2000 mic

Im currently running the guitar directly into the pc via the X3's USB out, i have no way of recording my mic (as it is a condensor) directly into my PC, so if i want to do vocal recordings i have to do it therough the HD16 and then copy the wav files acorss to the pc via usb... slow and annoying. I want to sell my HD16 track recorder and get a good mic preamp/guitar di interface to connect to my pc

I'm also looking to by a marshall JVM 410H amp (with emulated cab output) for recording and then to sell my X3 pedals to buy some stand alone effects etc like delay.

So heres the Questions.

1) What interface should i buy? i dont have a large budget at all, looking at the M Audio Fast track pro and ultra to record both mic and guitar.
2) should i be concerned with word clock? or is this not going to be relevent to me? (i dont want to have out of sync music)
3) Should i go firewire or usb and why.

I'm trying to create rock/electronica music so using samples for bass, drums, effects etc, using my own vocals and guitar playing.

before anyone tells me to read other posts, guides etc, ive read TONS of infomation across the net, and have a reasonable idea of what i need, but its always the things you dont read/think of that count.

THANKS IN ADVANCE :D