2 squads with all range and 1 with all armor is good with xp hunting, since u can easily adjust the number of armor and range u bring into the xp hunt.
however this means u'll need to move at least 2 squads every time to make sure there are armor going with ur range
but to answer about damage, unless u're going for an equal battle (which is pretty bad and should be avoid at all cost), don't use damage in ur army.