Re: air compressor question
To use a HVLP spray gun like that you will need at least a 5HP compressor.They use a large volume of air at a low pressure to carry the paint. Tank size matters as well since a larger tank means that your compressor isn't coming on as often.
MMotorBike is certainly right when he says that a Sata is the gun to have but I've used inexpensive guns like the one in your photo and they give an acceptable job if your careful.
If your just painting bikes or small areas they will work well.
The basis for a great finish is prep work. As was mentioned sanding with finer and finer grits, dusting your work with tack rags to get all the dust will go a long way to perfection also. Paint quality plays a big part also. Cheap paint is usually just that.
Hope this helps somewhat. I've had better that 50+ years refinishing furniture so this is what I'm basing my knowledge on.