that image is from when you when you decide to not have lunch with Korg, just only Ste and you add aphrodisiac to the food. But like I said earlier, the scene might play different if you're a top (but I can't say for sure cause I never checked that out).
Well fingering works cause it involves penetration in any way.
The scene with Korg and Ste is only a handjob, there was no actual sex with them if you're a bottom, again- not sure what happens if you're a top.