This is the second question on OFPEC I am capable of answering.
In the unit's initialization field put:
removeAllWeapons this;this addWeapon "AK47"
Remember, with the above code I've taken ALL the unit's weapons away, so you might have to put:
removeAllWeapons this;this addWeapon "AK47";this addWeapon "HandGrenade";this addWeapon "HandGrenade";... etc.
You can also do this through init.sqs if you know what this is. In init.sqs however, replace all the 'this's with the unit's designated name.