Honestly? This is my opinion, but I say no, it's not ok for you to wait in line and then have your husband and kids jump in with you - especially if they have to push past other people to do it (which is what would have to happen in most of DL's queues). The exception might be Nemo, if it has a very long line - just because it is so long. And most of the queue is along walkways and accessible by ducking under the rope instead of having to push past people.
As far as saving spots for parades/fireworks - yeah, that's perfectly fine. For the fireworks or Fantasmic! I'd recommend that they try to get back with you at least 15 minutes before, especially if you're fairly close, because people get packed in so closely (especially for the fireworks, where they make EVERYONE stand up about 10 minutes before the show) that they would have a hard time getting to you if they wait until right before.
If you'll be there in 5 days you can expect this weekend to be quite busy (because Disney's HalloweenTime starts on Friday) but if you're still around next week it should be pretty quiet, so you won't have much in the way of lines.