As far as resolution, that's probably good enough for you.
Regarding the noise. Adding filter caps should smooth out the ripple, the largest ones you can afford.
Also , for the ripple , the way to tell if it affects your readings is to see if the values go up and down. If they are filtered somehow then they won't show up in the data but if the data shows the voltage "zig-zagging " up and down instead of following a steady rate then I would say the ripple is a factor but your curve does not show that. It shows a steady increase so the ripple is not a problem.