There are other people who are better targets for your non-technical questions than the senior engineers with whom you have a brief opportunity to talk. Use that time wisely.
The HR staff will say misleading things and present a rosier picture than the technical staff. The technical staff are the ones who know what the sociological issues are really like, and the degree of happiness you experience in the job is likely a lot more related to how the other technical staff answer the questions than non-technical staff.
Saving all this stuff for HR is a huge mistake. You won't get any useful info.
Saving all this stuff for HR is a huge mistake. You won't get any useful info.