Speaking as a user of spark on mesos Yes it appears that each app appears as a separate framework on the mesos master
In fine grained mode the number of executors goes up and down vs fixed in coarse. I would not run fine grained mode on a large cluster as it can potentially spin up a lot of executors and DDOS the mesos master. In a shared environment coarse grained seems better behaved as you can cap the number of executors with spark --conf spark.cores.max and the executors stick around as opposed to growing and shrinking per stage.
