Labour i dunno how much, u wan u pay me, i do for u lor...but is
fix speakers only har..haaaaa
Speakers all can be used wid amp, using amp is jus giving more
powerful sound to come out of the speaker..amp also hv to find
sutibal amp..cannot say get a underpowered spk to connect the amp,
it will burn the coil in the spk.eg: 200watt rms spk driven by a
1000 watt rms amp.but very seldom can get such amps lah...cos too
expensive...
For woofers is better to connect to amp, as low frequency is harder
to produce by those little 5" to 6.5 " door spk as they are more
from mid bass...when u wan bass, the spk sound come out from those
small spk will be distorded if u dun hv woofers, long run become
"piak"piak"piak" sound...
U can D.I.Y to save money also...some screwdrivers (take out the
speaker)&(disconnect the wire behine & connect it back to
the new speakers) u are done liao..ur spk cannot be bolted down by
nuts & bolts mah..or welded right.. 
