De Broglie and other Quantum Questions

Hi, just some quantum physics questions. I've given them all a good go, the first two just require checking, but the rest I'm rather stuck on. They're the last questions in about 20 other ones, and my head now hurts. :(

Any hints are very much appreciated!

1. The problem statement, all variables and given/known data

I firstly got converted the 5eV to joules which gave m 8 x 10^-19. I then divided that by the planck's constant to get my final answer of 1.21 x 10¹⁵Hz

I got the wavelength of 2.49 x 10^-7, by dividing the speed of an EM wave by the answer to A.

I'm afraid this is where I get stuck. The possible equations that I know are KE = 0.5mv² and hf = φ + ½ mv²_max but here I am unsure of the theory. :(

Pretty sure this is the particle model. Unsure of how to calculate the wavelength though, any ideas?

I'm pretty sure this is the wave model. Same as the previous question.

Thanks for reading!