I suggest you find some resources on Gamma correction, there are plenty available online. All these factors depends on what medium your final output will be, for example broadcast projects are always 8 bit while film should be minimum 16 bit.
If you are working on broadcast, you can stick to default srgb color space since it doesn't really affect much unless you are specific about HD Rec.709, in that case you may work on 16 bit just to save more information while converting your file to Rec.709 in your comp app.
I really recommend you dig as much as articles you can find regarding gamma correction and then you will have a better idea about this whole subject.
Here are two useful ones