two simple plumbing questions

allright, first of, kitchen sink
it has a single handle on it to open and mix between hot and cold, all that works

it also has a spray thingy, im sure it is meant for doing dishes, but i like to use it to fill my coffee pot every night, so you can see it is important

anyways, when i grab the handle, instead of diverting ALL the water to the spray nozzle, it seems to divide it between the nozzle and the faucet

so, question one, how do i fix this?

i have allready taken the whole nozzle apart and couldnt find any issues in it

ive been told there is a diverter cartridge in the handle, do i need to replace this?

and this is where question #2 comes in, the little shut off valves in the cabinet i can NOT get them to close
are they made of chinesium or am i just an idiot?
there is a valve in the faucet at the bottom of the faucet neck could be dirty may need to replace the faucet due to not being able to get a new valve if needed