Ah k, well it sounds like your quite fit with that body fat at your age. Test should always be the basis of any first cycle just to see how your body reacts to it. Also because it is produced naturally in your body the side-effects are predictable.
Unfortunately regarding oily skin and acne, chances are you will probably experience this. For myself, I didnt see anything through out the whole cycle, and thne about 3 weeks after I finished for about 2 months I had it popping up on my chest/back etc. Everybody is different. However I am 23 and sometimes get bad skin anyway so i kind of expected it. My best friend has good skin all the time and got no acne coming on or off - so if your skin is good now you might not be prone to acne. Acne is a result of fluctuations in hormone levels so i guess its just a risk your going to have to take.
I wouldnt consider anything but good old test for the first cycle. You will still make gains if you use 400mg (200 mon & thus) or even 300mg.
The most part is training everyday and diet.
keep protein around 250-300grams a day. 6 meals a day - each with protein, shakes between meals etc.
and train hard.
anywho ill let you research the rest by yourself