a) add 3 add 11 so 35 and 46

b) perfect squares so 100 and 121

c) divide by 6 then 5 then 4 then 3 (the next two numbers are found by diving by 2 and then 1 so 3 and 3

d) check the differences between the numbers 1, 8 , 27, 64 all perfect cubes so the next two perfect cubes are 5^3 (125) and 6^3 (216).
Adding 125 to 103 = 228
Adding 216 to 228 = 444

e) check the differences between the #: 729, 243, 81, 27 all powers of 3 (3^6, 3^5, 3^4 and 3^3) so the next two differences are 3^2 and 3^1.
The pattern is also -, +, -, + so from 210 subtract 9 and then add 3
201 and 204

Interactive Blank Kakuro here

Looking at the first two cubes from left to right, the face opposite to the 6 cannot be a 1, 3 or 5 since they are immediately next to the 6. Also if we position Cube 2 so that 6 and 3 match up with Cube 1 then 5 and 1 are on opposite faces.

That leaves 2 and 4 to explore.
If we position Cube 3 so that the 3 on top of Cube 3 is is up against the 3 face of cube 2 the 4 will be on the bottom and 5 will be opposite the 1.
If we position Cube 4 so that the 4 and 5 are overlaid on Cube 3 then 3 and 2 are opposite one another.

So if we have 1 and 5 on opposite faces and 2 and 3 on opposite aces that leaves 4 and 6.