I have found the press and peel stuff to be very unreliable. I use the Injectorall photo etch system and Eagle PC board drawing software. With the photo etching, I routinely draw 10 thousandth inch lines with 5 thousandths between them. The most important thing is that it is repeatable, and the master print does not get destroyed each time.
As far as ferric chloride is concerned, I reuse it many times. When I go to etch, I heat it up to 125 F. The etching time is around 5 minutes. Use a foam paint brush and lightly brush the board while it is etching. This helps clear the reacted etchant and copper chloride that has formed.
Do not drink it, do not breathe it, do not allow small pets or younger siblings to wallow in it...Blah,blah,blah. It will also destroy most clothing and piss your spouse off if it touches any of their stuff. Remember...Darwin is always looking for a few good morons! <grin>

Ron