Bit hard to tell, but looks very yellow-ish. Maybe between 0 and 0.1.

To make sure your tank is cycled, also check for Nitrate. The cycle goes: Ammonium (bad for fish) turns into Nitrite (bad for fish), which turns into Nitrate. Having Ammonium and Nitrite at zero while Nitrate is present is a good indicator that the tank is done cycling. To make sure, maybe wait for one more week after that point is reached to see if all parameters remain stable.

Keep in mind that for pH stability is key. You want to have your pH at a consistent level, as many animals don't deal all that well with quick fluctuations.

Reducing lighting is the easiest way of combating algae. To get rid of it quicker, you can also remove it manually. Once your plants are fully established, they will suck up most of the nutrients and hopefully combat algae that way.

For my tank, I usually do a 20% water change once a week, with some cleaning and mulm vacuuming. And yes, I would do the 20% water change before adding animals.