I'm getting a Mallika and Pickering from PIN this week and asked their staff about fertilizing and what they use. I am perplexed by the exclusive amount of potassium folks give their mature trees at this site. They confirmed my feelings - follow a balanced 3-1-2 ratio for the younger trees and come time to fruit, increase the K (potassium).
Look for blue colored pellets in the soil. That is a slow release nutrient charge. But, I'd still ask the grower what they use. You don't want to burn the sensitive roots.
When it comes to tropical plants, I'm a N freak and give my trees a 12 month slow release 18-4-9 with micros.
Regarding pots, consider pots that terminate, prune, root tips. This affect induces strong secondary, lateral root output behind that terminated point...a very fibrous root ball that increase water and nute uptake.
Translation - double your vigor and production while halfing your pot size. MicroKote or Rootmaker products are your friend.
Mark