I am new to spreadsheets. I am in over my head but eager to learn!

I have created a google form to track a service technician’s daily time record. The technician might visit multiple sites in a day. As Forms does not allow looping questions, I have had to create a number of duplicate sections. The Google Sheet attached to the form is here:
https://docs.google.com/spreadsheets/d/1ur7eeJnEXZRNy9oWrSLpC_uD7d_c9p94gCNkuXVf2Oo/edit?resourcekey#gid=185521600

I have a couple of questions:

**1) Is it possible to filter within a single row to extract data? **
I would like to be able to SUM the “Durations” of different time “Types”. For example, “Office Time” column (BN) would be SUM of “Duration” columns if the Corresponding “Type” = “Office”, “Site Time” column (BO) = SUM of “Duration” columns if the Corresponding “Type” = “Service” or “File Job” etc.

2. I am trying to calculate the “Travel” as the difference between “Finish” of one Entry and “Start” of the next. I figured I could just SUM (Start2-Finish1), (Start3-Finish2)…etc which works great if all the entries are filled. (BP3 should = 2.25 but comes up as -13.75 as there is no value in BG3)
   Is it possible to write a formula to do this until the entries that have values and stop when the entries stop or would this have to be done with a script?

Thank you in advance for any input!!