What you want to do is to wet the ENTIRE media but to do that you need to water slowly to allow the media to soak up the water. If you are in cloth pots and water starts to run out of the side then you are watering too fast.
The yellowing could be some sort of lockout. Typically, yellowing and crispy edges means calcium or magnesium deficiency. The bugs, to me, are just a sign of a plant that isn't 100% healthy meaning its defenses get lowered a bit which will attract bugs. Like anything in nature, the powerful prey on the weak. If you have bugs it usually means your plant has something going on it doesn't like or that you aren't giving it.
The plant has good color so it is mostly healthy but might need some cal/mag supplementation.
If you want to try and eradicate the bugs I would start with an insecticidal soap solution. This is the mildest way for you to kill an infestation as long as it isn't too bad. Water, dish soap and vegetable oil. Spray the entire plant down. top and bottom of leaves. Bugs like to hide and lay eggs on the bottom of leaves where they aren't exposed.