I honestly couldn't tell you how long DS takes/took. He's done after 2-3 mouthfuls usually.
If I wanted him to eat any decent amount, it seriously drags out over much longer than your LO and it involves him out of the chair and coming back when he's ready for some more.
I know it's frustrating but their attention span is seriously about 20seconds, and we as adults have learned through social norms that we sit and eat our meal and eat everything on our plates, but they aren't yet bound by such things.
My little guy still wouldn't eat half that amount so all bubs are different. He sounds like he's telling you when he's done. WRT the fingerfood, that's a skill that takes a while and if you persist you will notice it improving and more going in that on the floor.