I don't think it would be practical to try pull off a cornrow with a full cap.

Those pictures you posted look like a fullcap to me. I wear a hairstyle similar to that. Thing I love is you don't have to worry about colour, texture length or hiding the lace on the edge of your topper. On the nape (back of the neck you can make out where his real hair begins, because of the bump). Hairline and temples look really good in that picture. It's just your imagination that they aren't right. Your trying to find fault in the picture. No one's face or hairline is perfectly symetrical. If you stair at one particular feature on a person for too long it stands out as being strange. I used to do it with people's noses.

If I were you I would begin with the first style you mentioned. There is alot of wiggle room with that style. Imperfections are easily disguised. Great thing about a fullcap is, you can quickly change styles. Once you become better at wearing hair you can always try the cornrow style. Please post a picture afterwards, I would love to see it done. I'm sure JRob would too!

My advice for making a template is; look on youtube for how to make a template. Also look at many pictures of various hairlines, start to think of a hairline as something that frames the face. Choose shapes that will suit you and hopefully you will end up with a natural look.