Re: First and second focal plane
They don't cover more when you adjust but many of them cover more from the start so you can see & use the adjustments at lower powers. Other than specific reticles designed to be thinner in a FFP scope, most are of a thicker subtension than their SFP equivalent, which is why most Benchrest and F Class Shooter use SFP because the reticles cover less of the target from the start.
In a FFP, it's always the same, but it depends on what reticle you get, some can be very thick to start like a P4, or even P3 type reticle. Many people find, the thinner FFP reticles are useless below 8X because you can no longer see the dots or hash marks in order to use your holds at say, 6x... at that point they just look like a duplex.