Older players might injure more, but they are way less expensive a choice for a "fill in" when someone who are keeping is injured.
I think ideally you want younger players as the majority of your team (a good reason to try to stay in Cup to make $), but the other players I consider skill point attributes over age.. especially when the budget $$ means all affordable are older.
I am not one to ask about counter formations. Hopefully someone else will comment with ideas.
I usually play variations of Maple Leaf. Since his module is very defensive, I would probably play 3N 2DMC 3W 2 red arrows wingers.. but that is a formation my team has played a lot and I know which players get the better ratings in that module.
Your team might not perform as well in that formation. I think as a manager you should decide what formation and orders you think utilises your best performing guys, and attend the match to make changes if you can.