In the paleo world, monounsaturated is considered way better than polyunsaturated, and saturated is considered the best. It's to do with the capacity to be oxidised (a bad thing) - the more double bonds there are in a fatty acid, the higher its capacity to be oxidised. Monounsaturated has only one double bond, so it's pretty low capacity. Saturated, as you can tell by the name, has the lowest capacity as it is already fully saturated with no double bonds available for oxidation.
Try a read of this http://www.marksdailyapple.com/fats/#axzz2L5MSjbqo
I don't really know about half-assing the diet, but would guess that presenting your body with carbs and saturated fat to dispose of at the same time isn't great - I think at any one time it handles one or the other best. Even then it might be ok if the total calories is not excessive. ie don't have a triple bacon cheeseburger and large fries and full-fat coke and supersize everything and fuck it a milkshake why not.
Depends - on the assumption that you're eating enough calories, where are they coming from if your intake of fats is low? Some people report success on higher-carb lower-fat paleo.
A diet has to work, and it has to be sustainable. If you don't like this way of eating, you simply won't keep at it long term. Paleo may work, it may not be sustainable for you. It's a great diet, but it's not the be all and end all - you should tinker around and find out what works for you and what doesn't. Eating a diet you hate for the health benefits will result in no health benefits in the long run, IMO. Don't necessarily bail out straight away, but you've got to find what works for you.
Legumes I have no opinion on - it's one of the less convincing aspects of the original paleo recommendations, but I don't eat them much myself.
