autocad 04 and sheetcam (and corel?)

[gary42095]

can someone explain to me please why some files while i am making the layers to cut (usually inside/nothc, inside , inside no lead, outside---- or something like that. sometimes there are files that when i select to make layered dont change to my selected color. like this file posted here http://plasmaspider.com/viewtopic.php?f=6&t=8944.
and also i was trying to mess with corel and autocad (not had much time to play) and this same files is all segmented lines when i put it into sheetcam will the simple combine tool fix the segments or the join curves if its the join curves what kind of gap tolerance/ radius am i supposed to use. i dont mind messing around, just dont waht to change things so badly i cant get them back to normal

thanks for any help on this,
gary