OK, now we are getting somewhere...

The synth voices are stored in banks (of voices). So when you want to select a new voice, you select a bank, then select a voice from the bank. You'll have to check the manual/data lists for the djx for more specifics as Im not familiar with the djx.Whats it good for? more banks equal more voices (usually).
You can loop anything. Besides samples, you can loop midi sequences(remember almost anything can be made into a sequence ie. notes, bars, phrases, chorus', even effects and control changes). Write out a 16 bar pattern/progression, then loop it to create a much longer song....
Styles? again Im not familiar w/djx, but if referring to the styles in xgworks the answer is no, none on the net(version 3.0 has more though).
Did they make a new djx? ....I dont know check with Toys-R-US (just had to get one in, couldn't resist).
midi capabilities? Well if you connect your DJX's midi output to the input of a MU128, then run an line from mu128 to a speaker and turn down the volume on the djx all the way, REALLY GOOD sounds will come out of the speaker...no joke....

keep asking question....
DudeManCentral