For (a), you are given ph=35 at x=0 and ph=15 at x=0.1, so since the variation is linear, . The 200 is , which is what it needs to be to get ph=15 at x=0.1.
In (b), is it correct to just subtract the oncotic pressure? If that's correct, then .
The units of k are the same as j/p, j is in cm/sec and p is in mm Hg, so k is cm/(sec mm Hg).
For part (d), you are integrating over the length of the capillary, x=0 to x=0.1. Call the volume flow rate Q. The volume flow rate through a small piece of the capillary with length dx is j times p(x) times the area. You get p(x) from part (b) and the area is the area of the side of a cylinder of radius r=0.0004cm and height dx, so it's . Putting it together gives , and since r and j are constants, . I assume you can take it from there.