- Yes, someone can believe false propostions about God or how to seek him and still be meaningfully said to be seeking God. Peter Kreeft gives among the standard arguments for the existence for God, the "argument from Bach," which is basically if there is no God, how could the sublime music of Bach exist. That might sound stupid, especially if you're not a musician, but the point is that even something like music points to transcendent qualities, and moves people to conversion more often than you might expect. For people who practice false religions, it might not avail them of salvation, but it that doesn't mean that they are not seeking after God (even if they misunderstand God), and in some cases they may even come to genuine conversion.
Also, as an aside, Buddhists do not worship a man Buddha. If they view him as just a man, they do not worship him, and those who do worhip the Buddha (or multiple Buddhas) view the Buddha as a divine figure, not just a man.
- There's nothing wrong with "mysticism." Have you read anything that St. Ignatius of Loyola wrote?
- If you want to split hairs, what Francis implied in that sentence was that God loves the "existence" of that person, which is an objective good even for the most evil person, not their homosexual inclinations or any homosexual acts.
- You are reading too much into words that were likely either off the cuff or not prepared with much thought. Again, he didn't say that God was unable to do everything, he said that God was not a magician with a magic wand able to do everything. He does not say that God cannot do everything, but not as a magician with a magic wand. The intent is not to deny God's omnipotence, but to affirm God's use of secondary causes. And in this quotation, I suspect that the English translation is not a great representation of the original Italian.
Did I ever say that the Church is a building? The Church is a body of people, those who belong to Christ throughout the world, and can be outside or inside. However, the Church is a visible, not hidden, body and it is hierarchical with different roles and positions of authority.
If you want to understand Catholics, instead of parsing cryptic newspaper quotes from Pope Francis, you would be better off reading the writings of the saints.