Just got a new 2003 350z last week.

There is a strong gas smell you first start up the car.
The owner did say there is a minor and intermittent oil leak in the fuel injectors area. But it is very minor doesn't drip down all the way to the floor and happens very rarely (has not happend yet since I got it). Owner did say we should't be that concerned over getting it fixed. He said something about getting one side of the engine fixed but not the other side years ago.
Should I take it to a mechanic and get compression and leak-down tests done? or should I leave it alone. Because I do not want any additional oil loss on top of the natural oil burning.

Additionally, please recommend a good engine oil type/brand to use. (available in Australia btw)

I checked the dip stick and it got oil but it's dark af... what does this mean?