do krox in skink units have to be in the second row or can you have them in the front row and just use the skinks to give them ranks was curious if the rules say you have to have them in front
Yes, the rules in the book state that you must place the Kroxigors in the second rank, unless the front rank consists of less models than the rank behind it. See page 41 for full details.
think ultimately the point is that if you want skinks to give your krox rank bonuses then you have to have skinks up front and the rest on the sides and back and the fronts ones will suck and die...no way you can have enough skinks for rank bonuses and still have krox in the front to soak up attacks and save the skinks
Yeah they can attack, as said in the armybook with their "great reach" ability that makes them swing over the first row of skinks.
Yes, however you can only have one Kroxigor for every 8 Skinks, so that would mean you'd have to have 160 Skinks in that unit.
In a unit with only Kroxigors, you would be able to make ranks with a minimum of 5 in each just like most other larger units (Minotaurs & Ogres for example). But certainly their effectiveness would go up almost 400% if you were to field them in separate units instead of just having over 800 points just to gain +3 rank bonus. Imagine even 3 units of 5 charging a single unit in the front and flanks - that's a lot more than a measly +3.