David calls himself "your father" because this is a very formal occasion. Alternate translation: "my God" (See: [[rc://en/ta/man/translate/figs-123person]])
Here the "heart" the represents the whole person. To do something with "your whole heart" is an idiom. Alternate translation: "with complete devotion" or "completely" (See: [[rc://en/ta/man/translate/figs-synecdoche]] and [[rc://en/ta/man/translate/figs-idiom]])
Here the "spirit" represents the whole person and emphasizes the person's will. Alternate translation: "willingly" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
These two phrases mean basically the same thing and emphasize that Yahweh knows the thoughts and motives of every person. (See: [[rc://en/ta/man/translate/figs-parallelism]])
Here people's "hearts" represent their feelings and desires. Alternate translation: "searches everyone's emotions and desires" (See: [[rc://en/ta/man/translate/figs-metonymy]])
This can be written in active form. Also, this speaks of following Yahweh and having him listen to you as searching for him and finding him. Alternate translation: "If you seek him, you will find him" or "If you try to get Yahweh to pay attention to you, he will do so" (See: [[rc://en/ta/man/translate/figs-activepassive]] and [[rc://en/ta/man/translate/figs-metaphor]])