Yes... unless you have a 5th choice if you go really small mana guys... I would try to always keep my snipe protected as much as possible since he is usually range and usually small health... The one exception is if you use the Spirit of the Forest, I think she can handle herself in the 4th slot ;) (she's a beast of a snipe and I like her a lot here on that) :D

On the second point, given the 4 choices you gave (which there are many potential combos)... I'd put the snipe-magic guy in front of the ranged guy in the 2nd hole unless you have a beast of a tank that will last the whole game... The reason is if your tank goes down, the 2nd slot will move to the first, and then your range guy will cease to attack anyone. Lots of moving pieces, but that is what will make this game fun :D