Better Bass Techniques? And Mix Down Prob, recording bass n pro tools free Options

[mancabbage]

yo, ive been recording a demo for my band using pro tools free and an imic - we've been feeding everything through a P.A system and the results are amazing quality, apart from the bass, see our bassist plays a 6 string funk slap style bass lines he does the same amount of low notes as he does high notes - thing is on the recording the high notes are really noticble but the low notes arent - i could boost the gain and this makes the low notes sound much better but the high ones like complete shit - so is there anyway i could boost the gain of the low end ofthe track more than the high end? how? maybe i could use a different recording technique: at the moment we are using a line out - into the pa - into my mac - would it be better quality if we mic'd up the amp instead????

also in pro tools how do u mix down some tracks , but not all of them - see we have our vocals spread over three tracks , which witheverything else takes up three tracks - so how do i select these tracks and mix them down into just one track? so i can make room for the others??