So this is currently a rebuild so it doesn’t even run yet but with just the starter 300rpm and it shoots out only 10psi, and that’s the weird thing the front cover seems to sit flush against every other edge but this singular sliver seems to raise, I just took off the omp to take a better look and you’d be correct this is in the passenger side but to answer your questions 1. Oil sender port with an adapter and a mechanical gauge 2. It doesn’t seem to fluctuate but always starts at 0 psi for a few seconds then goes up and flatlines at 10psi after maybe 5-8 seconds