Improvement of plugin operation

[z1le]

I've looked at many plugins of this type and I like yours the most, but I'm missing two things that I don't know how to implement.

1. singular and plural on frontend timer
   if = 1 => day; if>1 days,
   if = 1 => hour ; if>1 hours,
   if = 1 => minute ; if>1 minutes,
   if = 1 => second ; if>1 seconds,

2. when the time expires, the possibility of writing a text . For example "this offer is finished".