I made some diagrams to make it easier for other people to follow along the solution:
Problem 3 solution
It might look like white is winning, since both sides have 4 “territory” and it is black to move. But white’s territory is defective (C1 and D2 are miai) so this is actually winning for black.
If white tries to cut with 2, white dies first. In normal go white would have the snapback at B1, but in capture go A1 is a real eye.
I think the next one might be sligthly easier:
Problem 4:
Demo board