Convert here, too. I’ll try to answer the best I can and hopefully someone will correct me if I am wrong.
Along those lines, are we only supposed to ask Saints to pray for us? Or do we ask them to directly intervene with a situation? Do they have the power to do that, or only to pray for us?
I do a little bit of both, depending on the situation. Usually I ask a Saint to pray for me. But sometimes I think of them sort of like Angels, who can intervene on God’s authority. For example, I once asked Padre Pio to do something for another person who lives across the globe. Of course, I asked it only if it was in accordance with God’s will. I have also often asked St. Francis of Assisi to lead my dog home when she has gotten loose. Today I even asked him to nudge her to come inside when she wanted to stay out in the yard and I needed to get my daughter to the doctor. St. Francis has never failed me on that account.

I have also asked St. Rita in the heat of the moment to give me strength - I got it - along with peace.
Don’t get too wrapped up in technicalities - as long as you understand that all glory and honor is reserved for God alone, and that nothing can be done without his will, then it’s OK if you slip once in a while in how you phrase your requests.
Yes, the Virgin Mary was on my list today. Along those lines, my gateway to Catholicism was Scott Hahn (Catholic author and apologist, he’s fantastic!) He talked about praying to Mary for the first time, (like me, he converted from Protestantism), and then forgot about it, only to see his prayer answered 6 months later. I really do get the sense that Mother Mary listens and answers, based on his story, and yours. Will be most interesting to see what she can do about some of the “tough nuts to crack” on my list of…challenging people
Just be aware that often, when we pray for a situation with another person - a tough nut to crack’’, so to speak, it is us that end up doing the changing more often than the other person. I would recommend the Rosary for these types of situations.
When you say that the Rosary is “powerful,” how so? In what way is praying a rosary more effective than without? Does it have something to do with helping the worshipper meditate on/pray for the right things? I really do think I could use some help in that area. I don’t tend to “sin” in big ways, but the beatitudes, well…I could use a good dose of humility and more charitable love for others. I also don’t “worship” God enough, rather I endlessly petition him for help. Maybe a rosary would help me get my prayers back on track and relate to God in a more humble way.
I think that just sitting down and praying it is the best way to learn the answers to these questions. I could try to explain what I have experienced in praying the Rosary, but I think it can be such a personal experience, it’s difficult to convey all that can come out of it and how magical and mysterious it is. But I will say that Our Mother promises to grant many signal graces through the Rosary - I went through a time when I was first exploring the church and I was going through something very difficult and naturally fasting as a result of that, as well as praying the Rosary. I was getting answers to my prayers left and right - it was amazing. Also, the meditations can touch you in a very personal way - I couldn’t get through a Rosary for the first few months without crying.
The Rosary can definitely help bring you more humility. I would suggest you pray directly to God for humility. (And my experience has been that if you need a good dose of humility, God doesn’t have a problem dosing it out!) But praying the Rosary and reflecting upon what Jesus and Mary have given to us - how much they have suffered and how purely they have given out of love for us - that certainly has the effect of bringing someone down a few notches.
Generally - just give it a try. Just talk to a Saint or two, (or three or four). There are formal prayers that you can find online or on prayer cards, but you can just talk to them also. Good luck!