Brentford will want to not lose points from this match. They will play today for the purpose of drawing the match. Winning such matches is not easy.
I don't think so, at least I hope that isn't their approach. They are actually a pretty good attacking team, and that surprise element, despite Arsenal probably being aware of it, will have an effect on Arsenal. Plus, its the first game of the season, a lot of teams will still be shaking off cobwebs, if Brentford come into this motivated, and attack it from the off, that's their best chances of securing points.