Selecting an arduino (and accessories) to buy

Hello,

I made a buzzer system using a PLC. The problem is a PLC processes the lines of ladder logic too slowly and I end up with two inputs activating results at the same time. I could fix that with tie breaker logic in my ladder... if I hadn't already used up nearly all the lines it allows. A friend suggested I get an arduino instead. He will program it for me, I just need to buy it.

I need something that can handle around 25 inputs (just simple normally open or closed buttons).
It also needs to handle around 20 outputs (I have a bunch of lights that indicate the digit of the buzzer that rang in, and a buzzer). Alternatively if there is a simple screen that can display digits up to 20 instead, that may work better.

I don't know anything about Arduino and trying to look into it just confused me more.

Thank you for your time.

https://store.arduino.cc/usa/mega-2560-r3

Excellent,

Thank you very much.