How to pause/resume transfer of large files?

I would recommened using rsync.

Example:

rsync -a --append source-file destination

If you want to see the progress, add the --progress option to the command.

short answer, need no installation, to pause use kill -STOP PID
to continue paused process use kill -CONT PID
where PID is Process ID. you can get PID by running System monitor or top command

I can answer only the part about the difference between terminal and nautilus. I have checked several times this. It appears copying from terminal is faster than any graphical way like nautilus. At least in my case, when i copy about 32GB of info, it takes about 3 to 5 minutes less from terminal than nautilus from a 25 minute copy. that is about 10%-20% of the time. About a way to resume a copy to your external unit i think curl or rsync would resume a failed copy. At least with cp command. I have not tried this myself (I will try tomorrow) but this two might work.

For curl you need to aptitude install curl or apt-get instal curl since it does not come with ubuntu by default.

Use curl --help or rsync --help to find out more. Tomorrow i will show how to copy with both if you could not find the way.