If you want to just play BO1 with this deck then go for massive amount of 1-drops and 16 lands. Having that many lands gives you over 80% that you will get 2-4 lands in opening hand. Knowing that Venerated Loxodon should be your main goal to obtain for that kind of deck. Rustwing Falcon is good enough to add as another 1-drop.
I don't know any Boros Aggro decks that would play Settle, but regardless that's normally public enemy #1 for aggro to play against. Shalai, Voice of Plenty or Tithe Taker can help, but honestly it's hard to say without knowing what your friend is even playing. The top tier Boros decks that appeared a while back was just White Weenie splashing for Heroic Reinforcements, or the angel build, but he might be playing a more casual build with actual Boros cards.
Overall strategy vs other aggro decks for WW is to get bigger creatures than oponent.
Obviously sometimes on the play the hand is so good it's just a steamroll over the oponent no matter what kind of white aggro version it is.
But if that's not the case the game is stalled and the one with more anthems and counters on creatures win. Flyers matter here as well.
Boros has Heroic Reinforcements but has to cut something for it and most of the time it's Venerated Loxodon. You can't cut 1 and 2 drops for it because the deck will be too slow then.
That said Boros is more explosive and has these 'nut draws' more often and most of the time you will be on defence. But mono W is more consistent and better at stall game. Unbreakable Formation is priceless in that kind of matchups. Getting free attack that doesn't cost you any casualities is gamebreaking in this matchup. You may want to play 3-4 copies of it in mainboard if you struggle with this matchup. Tithe Takers are rather bad in this matchup and I'd side out them for Baffling Ends. Ajani, Adversary of Tyrants is fine to side in as well but on the play - it's not impactful enough when on the draw.
If you see him pass with 4 mana untapped don't overcommit. Just go for the long game and it should be fine.
Am I limited to attacking with half my creatures if I sense settle the wreckage?
That's something you have to estimate based on board state. Simply put - don't do attack big enough to make counterswing lose you a game. You have to be sure that oponent won't kill you right away after he Settles you.