MacPorts installation processes

[Patrick Hinkle]

Sorry to ask these fundamental install questions but do I have to:
1.) Install MacPorts every Terminal session I run?
2.) After I have installed MacPorts (where the Terminal will accept
"port "-option"-type commands), do I have to re-install it every time I
terminate my Terminal session? or my operating system session (running Mac
OS X Sierra, 10.12.6)?
3.) Do I have to uninstall MacPorts at some particular time/phase when
using MacPorts?
4.) After performing "Source install" using section 2.2.2's installation
techniques I use 2.2.5's "MacPorts and the shell" and have entered:
export PATH=/opt/local/bin:/opt/local/sbin:$PATH
followed by 'port search', & 'port edit and I get the following bash output:

Version number in metadata table is newer than expected.

    while executing

"registry::open $db_path"

    (procedure "mportinit" line 642)

    invoked from within

"mportinit ui_options global_options global_variations"
Error: /opt/local/bin/port: Failed to initialize MacPorts, Version number
in metadata table is newer than expected.
Here, I am performing the "Source install" using section 2.2.2's
installation techniques & section 2.2.5's "MacPorts and the shell"
techniques - Is this Error just a product of me installing MacPorts more
than once or does it justify me using other techniques, like uninstalling?
Sorry for the lengthy question.
Thank you for your time.
Patrick Hinkle
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