For the TAT use:

=(C2-B2)*24

copied down. Format column As General (or Number).

Then in I2 you can use a formula like:

=COUNTIFS($A$2:$A$22,$H2,$D$2:$D$22,"<=24")

copied down

in J2, add another parameter:

=COUNTIFS($A$2:$A$22,$H2,$D$2:$D$22,">24",$D$2:$D$ 22,"<=36")

copied down

repeat structure in remaining columns.