How do you want this data presented in your portal?
You may indeed need calculation fields such as:
If (type of Hours = "Regular" ; Hours ; "" )
for each type of hours and then you can define a summary field for each fo these calculation fields so that you can get several columns of total hours in your portal, or you can use them for Grand Totals placed below the portal. (Calculations using Sum(), defined in the Parent table can total these same calculation fields for computing grand totals and will usually update more smoothly than summary fields if you are entering hours directly into this portal.)