What you are looking for are typically referred to as a Portrait lens and a Macro lens.
Nikon correctly call macro lenses Micro because the lenses are used to photograph small subjects than the macro sized world we normally photograph.
These aren't normally the same types of lenses. Portrait lenses tend to have a faster aperture, macro lenses are specially design to allow you to get closer to the subject and fill the frame, this comes at the cost of a slower focus system. That begin said you can use macro lenses for portraiture quite effectively so if you can only afford a single lens to do both tasks that is where I would look. The Nikon 60mm f/2.8 Macro would make a good portrait lens and has along enough focal length for some macro work on a crop body.
All true macro lenses will give the same 1:1 reproduction ratio, which means a subject in the real world that is 1cm big will take up 1cm on the sensor, so then knowing the sensor size you can see how much of the frame this will fill. It doesn't matter which focal length macro lens you use, all will do the same job. The difference is that longer focal length macro lenses allow you to be further way form the subject (called minimum focal distance MFD). For insects and things which can get scared you want to be as far away as possible but the longer lens are heavier, more expensive and harder to use.
For flowers obviously you can get very close.
For portraits you need to decide if you want full body length portraits, couples, small groups, indoor work - then the Nikon 35mm f/1.8G DX is perfect. If you want head and shoulders and close up details, or have space to work with then the the Nikon 50mm f/1.8 G or 85mm f/1.8 G are also good candidates. The 85mm is a little long but works for head and shoulds work if you are not too cramped. 50mm is somewhere in between.