Does doing a b/l barrage around the areas of lattice degeneration greatly reduce the risk of retinal detachment? are there any risk in this procedure?

Perhaps: It is recommended if there is vitreal traction, holes, tears, and/or is symptomatic. In that case, it can lower the risk of future retinal detachment. The risk is very minimal in competent hands.

It depends: Laser barrage can protect you from a retinal detachment from lattice if there are high risk findings associated like retinal tears along the edge of the lattice, history of retinal detachment in the opposite eye, marked traction/elevation along the lattice, etc. Many have no problems at all from lattice and do not require treatment.