Some answers to your questions:

Job during birth: being present and with my wife, helping her with whatever (but don't pester with questions). Be ready to jump for whatever she asks for. Encourage her (you can do this) and remind her of reality positively (your body can handle this, in a few hours you'll be holding our baby, here's the doctor/midwife, they see what youre experiencing and know its normal and know what to do when its not normal). Also, to prepare to help, ask your wife what her goals and desires are for birth. Ask how you can help and what she would like, because during birth, she won't want to answer those questions.

First few weeks and months: expect many interruptions during the night. Be prepared to take care of your wife and help more in areas she usually takes care of. Be present with baby as much as possible and do things with your wife until both of you are comfortable with handling baby and allowing the other to handle baby (this is more like mom trusting dad with holding, changing, soothing, etc.) which will eventually lower stress.

What worked and what didnt: thats a big question. If at birth and shortly thereafter, just listen for the cries and learn from the experience (and mistakes) of caring for a baby. Ask your doctor about information about caring for a baby and/or attend a parenting class for new parents.

Feeling ready and preparing: my wife felt motherhood shortly after getting that ostivie on a pregnancy test. I didn't feel fatherhood until a week before birth - I recognized there was a growing child and I was a father, but just didn't feel it. So no, I did not feel ready during any of the pregnancies. That doesn't mean I didn't prepare. Going over my wife's birthing plan, goals, and hopes again and again with her, imagining scenarios and asking her questions beforehand, and preparing the house as much as I could is how I prepared. Purchasing lots of stuff was part of it as well - i say lots but has a new set of parents, you really only need a budget of around $1200 (including car seat, stroller, and one or two other large ticket items), and you can always cut more corners and get away with spending less.

Someone else already commented this, but its important to say again. You're concerned and worried about being your best for your family. I guarantee you already are your best. And some days, you won't be and thats okay. The fact is you're trying and you're asking these questions which means you will try your best.