knowing where u live or zone will help.
depends on your goals but at quick glance and since trunk tends to be obscured.
see
http://bonsainut.com/forums/showthread.php?t=5798
id leave low branches alone remove all branches in middle area.
come spring repot and work roots. chances are they have long circling tap root, i'd try the hose clamp technique. repot in better soil. grow a season in smart pots. then in the ground.
one of the low branches will be first trunk portion.
keep one to torture eg. pinch candle wire etc etc. and let the others grow.
feed the mess out of them. you'd be surprised how hungry they are. and full sun if possible.