Efficient file copy from USB device under Buster.

[Richard Owlett <rowlett@cloud85.net>]

Due to low data cap and doing very customized installs I've generally 
purchased DVD sets {now available on a single flash drive}. The one I 
purchased has ISO's of both install and live versions on a single partition.

I wish to copy only the install DVDs to a single partition of:
  1. the laptop's internal drive.
  2. another USB connected device.

In the past dd has been convenient and appropriate.
This time I want only some of the files in the source directory.
I could use Caja or rsync if my only criteria was minimal keystrokes.

Thinking about this has prompted questions.
1. Using Caja or rsync -- are there options to minimize transfer time.
2. Can I do casual web browsing and email reading at the same time.
3. Can I take advantage of my processor having 2 or more cores.

I suspect I'm asking if Debian does multi-tasking &/or multi-threading.
That question implies I what should I be reading.
TIA