Paleo/primal/lchf, really, the differences are small- originally paleo Was more restrictive (Cordain et al) but the likes of Robb wolf (paleo solution), is more towards the Primal (he has cream in his coffee, also eats white rice when in intensive training).
Swedish lchf (see dietdoctor.com), is fairly heavy on butter and cream.
It might be easier to use the umbrella term "Ancestral woe", the similarities far outweigh the differences! All advocate a clean (additive and fake ingredient free) food, raised or grown as naturally as possible, and GRAIN FREE, soy and legume free (white rice being regarded by many as fairly benign). Potatoes... May be fine for some people, not for others, if they make you ill, don't eat them. Peeled or very young ones are less likely to make you feel ill.
HOWEVER, and its a big "however", whatever carbs you eat, you need to eat a lot less than the standard diet (ancestral doesn't mean "low carb", but the typical diet is so massively high carb that it seems very low in comparison).
For faster weight loss, yes people do cut carbs down very low (20g,50g, per day, but for maintenance I think 100-150g a day would be quite typical (about a third of what many people eat on a standard diet!).
For weight gain on paleo/primal, I hate to say it, but the nuts! 
I mean they are great, healthy and full of vitamins etc, but no getting away from the fact that they have a lot of calories. As Robb Wolf says, while not wanting to encourage calorie counting, "at some point, calories DO matter, be mindful of portion sizes with nuts".
That would be especially true while weight loss is the goal. Nuts and nut baking, nut stuffings etc are treat foods IMO! For adults anyway, for kids they can be a great source of calories and fat.
Breakfasts... Meat and berries, meat and cheese, meat, cheese and berries (think Scandinavian style platter)!
Leftovers make great breakfasts 
!