Vinegar Smell from Sourdough Starter
The vinegar smell is an indicator that your sourdough is growing up in a too cold environment. Without diving into the details of the various lactobacillae found in the average sourdough cultures, the simple rule is that a cooler environment favors the strains that produce more acetic acid while warmer temperatures are better for the production of lactic acid - the former being the acid in vinegar and the latter the much milder acid known from fermented milk products. 

As immediate measure, find a warmer place for you starter. Caveat: warmer temperatures will also mean more yeast activity, i.e. more bubbles and in the worst case, a tendency to creep out of the container, so leave enough room just to be sure.

The separation of layers is a sign that the microorganisms in your sourdough are starving - which can coincidally favour the slightly more robust acetic acid producing strains. Once your starter has been somewhat established, meaning you get a reliable activity after each feed, it’s better to learn from your dough which feeding cycle works best. Remember that feeding simply means supplying a certain number of microorganisms with food so that they can multiply. Warmer temperatures will also increase their growth rates, so you should take that into account.

Depending on the ratio of (starter) : (flour and water), feeding time can be every few hours or once every day and a half. Ideally you start with a chosen ratio and measure the time until it just starts to collapse again. This is the ideal feeding time. (measuring means you don’t have to rely on visual clues alone, but get an idea when to plan the next feeding.) If you have a very active starter, you’ll probably want to reduce the amount of starter for a given amount of flour and thus extend times between feedings. Do not go below 10% of starter or you risk spoiling: There won’t be enough sourdough microorganisms to keep the nasty kinds in check for sure.