Yes, Bora-Care can be applied either by spraying or painting with a brush onto the unpainted/raw wood surface.
Bora-Care is safe to use when yes, used as directed on the product label. It is a green product Unless you physically drinking the solution or ingesting the treated wood they would be no harm, it is a borate based product so slight contact with skin would not be absorbed or harmful and washing off with soap and water when contact is made would be recommended and wearing safety gear to prevent contact.
We really cannot guess what the insect may be. We recommend either trying to gather a sample of the pest for a pest ID or calling a pest control operator in to give a free or low cost inspection to help you make the pest ID. Once you know for sure what pest you have, you can choose the correct treatment method.