[jcynix]

>For your 1st issue, you can setup bash to append commands rather than overwrite them.

Good, but even better (IMHO) is to write one history file for each terminal window, shell and level as in

  export HISTFILE=$HOME/.history/${TTY##*/}.$SHLVL

And then I tell zsh to add timestamps

  setopt APPENDHISTORY            # don't overwrite HISTFILE
  setopt EXTENDEDHISTORY        # add timestamps to HISTFILE

setopt HISTIGNORESPACE # aka setopt -g set HIST_FIND_NO_DUPS # don't show duplicates on ctrl-R

Now I can grep my history and, based on other work notes I take, can even limit my search by date/time if needed.