Cleaning with bleach is OK. Dish soap can be a problem. When cleaning with bleach, rinse, rinse, and then rinse some more. Let it air dry for a day or two. If you still smell bleach, rinse more and repeat.
I looked up Amquel and Novaqua (going from memory here, so if I messed up the names) and on their site, it recommends using both, so that shouldn't be the source of the problem.
The pH issue is the fact that your tank is cycling and that is going to change the parameters. I don't know about plants, so I dont' know if that is the problem.
From reading here on the forum, you should only do a maximum of 50% water changes otherwise you'll take out too many of the good little bacteria.
You're going to need some ammonia in the tank to grow the bacteria, so you don't want to take the ammonia readings down to 0.
Here's a link on cycling with fish: http://www.firsttankguide.net/cycle.php