By ink stroke I assume you mean Toon Line render. It's not a plugin, it's a render option you'll see when you render to file. Under Options, click Toon Render to "On" and you can access different options, like thickness of line, whether to make the line black, a color, or a percentage of the object color, whether to render just lines or lines and color, shading options(partial, full shading, flat color), etc. etc.
There's lots of settings to look at and play with. You might want to look at either help files or the manual if you've got it. I can see from the manga style you're going for why you're wondering about texturing, and you're right, for this style you don't need to knock yourself out with texture maps! But like I said, under Surface settings you can set specularity and falloff, stuff like that that will give your "flat colors" more roundness and depth if you want.
I think there's also a "manga style" option for eyebrows,( at least there used to be) where the eyebrows lay on top of the bangs. If you look through the image galleries there's tons of manga style images for inspiration, and maybe you can direct questions to the guys who do that style, or at least ask how different effects are achieved specifically for manga.
EDIT: Hm I see there IS an InkStroke plugin! I'm completely unfamiliar with that!