是日已过，命亦随减，如少水鱼，斯有何乐？
IMO, the above is referring to evil no do, good do do like love
and bliss as well as sharing wealth to the needies and care for the
aged and sick, contribution to the well beings of the society. Most
importantly, to the monasteries as only proper education can impart
right value of life and death.
大众！当勤精进，如救头然，但念无常，慎勿放逸！
IMO, The above is urging 等觉菩萨and below to dwell
in Buddha nature remembrance and/or the beautiful scenery
and life in Amitabha land of ultimate bliss, and to rebirth
there.
精进 - doubtless and focus in any one dharma gate.
无常 - bad thoughts like harm towards living beings etc.
是日已过，命亦随减
In Saha world, any 150 years old living being still around and
how many ? Impermanent :)