There's a lot going on there
"Shark fin" i think is structural and fully welded as part of roll hoop structure. Wings, 2 of, are bolted either side of this fin. Flat 12 engine, in comparison to V block has torsional rigidity compromise in ultimate load it can take. Really twisting it from chassis loading pinches crank bearings, potentially.
Pipes travelling inside that are in chassis effectively.
Tank behind driver looks to be coolant header, and pretty normal for period.
Oil tank for dry sump was usually at rearmost of cars (end of gearbox) to facilitate all oil being there under acceleration load etc.
Mistery pipes through shark fin LOOK like vents from crankcase and head voids to vent any excess oil/air back into the oil feed tank to maintain oil volume (rather than just blow it out to atmosphere) in system if the engine gets a bit "windy" during race weekend. Quite normal to do that and not essentially pressurised as such.
The oil tank will usually incorporate some means of de-airation of content to feed only oil/liquid down to oil pumps and not cause cavitation, which will completely toast the bearings at high load.
That oil tank was often a vertical column type to facilitate the above.
Often an oil cooler was fitted near there, either for engine or transmission cooling.