Some very good info there and nice of you to take the time to post your findings
Being educated from earlier on about lap times it helps you understand a lot, it has me.
In practice I had a known fast guy tag along behind me for a few laps, it tells you where you are going wrong on your lines and/or if you can deal with pressure. Down the straight it can tell you if you're geared right or if you just have a bad motor too. If you have the speed but cant follow them on the infield then it is likely to be a setup issue.
Simple things to do if others around you are as friendly, and that is what club racing should all be about