Data validation or is there a better option?

Hello I am trying to create a form for people to fill in when doing assessments. I need it to have one drop down list and in that list they will have a choice of about 36 risks. Next to that I will need a column for mitigation (how to reduce the risk) but although I have 36 differant mitigations only one will match each option in the drop down list (the people using these lists will be clueless so I am wanting the correct piece of mitigation to auto populate against the drop down option). I then have a 3rd column for a score for the risk, each risk will either be a 15, 10 or a 5 no inbetween, is there anyway I can get one drop down box to auto populate the two columns next to it?

I then also need add the total of column 3 automatically.

I'm sorry theres so much and I hope that makes sense, I have used excel before but I have never had to create anything like this. My head is in a spin and I don't know where to start. I have got as far as making the first drop down and now I don't know where to go Hope the attatchment helps you get an idea of what I am wanting to do.

That is amazing thank you so much I have spent a week trying to figure this out. Once this project is out of the way I can see myself spending hours in this forum learning excel properly.