If you had a choice between a] defending Catholicism to someone or b] sharing Jesus' love and gospel, what would be do? Why should anyone, Cath. or non-Cath., care whether you can defend it?
First, I'll finish my original point, then I'll address some of your questions.
Doesn't it seem rather incongruous to you that a] you say you believe such-and-such and have "studied" it but b] you can't articulate it and need others to give you "guick to the point answers" to defend it? Believing is more than accepting assertions as true. Believing is getting making those truths so real that your life changes as a result. if your life has changed, share that with people. If your life hasn't changed, deep down on the heart level, something is wrong. (I don't mean, "now I'm a practicing Catholic so my life has changed).
Now for your points:
Of course history and teaching is important. But not as Catholics present it. Much of what they present are self-serving myths and religiosity that has nothing to do with one's salvation in Jesus.
Yes, I believe Jesus as the ultimate sacrificial lamb that died for us all. This is pointed to in the OT and taught in the NT, and Cath. is not necessary to learn or believe this.
I don't understand the point of your question about the Ten Commandments. But let me say that you can keep the 10 Commandments and still have a heart full of sin. You can avoid adultery or murder, but as Jesus pointed out, you can look at someone with lust or hate in your heart and be guilty of breaking "the rules". So keeping rules, only, won't ultimately help you; you need a change of heart as well. The law can't change the heart. It can only weigh it down.
I never said "Jesus died for my sins" and then left it at that. Of course the remainder of our lives should be dedicated to following him and learning from him and other Christians. What I mean to say it, instead of pointing people towards theology and cathecism, point them to the man. Yes, he was a teacher, but he did not come merely to bring a set of teachings that we follow. He came to bring himself. His teachings, in fact, are obsessed with this idea -- look to me, learn from me, come to me and I will give you rest. Not, adopt my beliefs and they will give you rest.
Yes, I strive to live a holy life, but one based on utterly depending on God for every breath and rejoicing while doing so. I do live a life primarily focused on keeping sets of rules. Jesus has freed me from sin, and the more I experience his love, the easier it is to focus on him and in doing so keeping the rules becomes my nature, not something I have to pressured into doing.
IN RE my pure heart: When God looks at me, his sees Christ's purity imputed to me. And I can experience his beautiful, joyful peace and grace without worry about whether "I'm good enough".
Where do I get my strength? From remembering the amazing times that God has been so present, so close, and so overwhelming to me, that any amount of suffering or fear/anticipation of suffering does not make me waver.
Now, I've taken some serious time with you, so you owe me.
Tell me about the sweetness of Jesus you experience in your daily life, and do so without theological language.
My friend, you are separating the two. If you understand the breath and scope of the Catholic faith, it cannot exist without the love of Jesus and the Gospel.
When you defend the faith, you defend everything that is in accordance with the love of our Savior.
There is not distinction.