I think that you are doing it the wrong way, this is why:

1.- If a plugin gets updated and the database too, you have to make updates to your api. So imagine the amount of updates that you are going to make for each plugin.

2.- A lot of plugins extends other plugin's classes of or require certain plugins and events.
The plugins are made in a way that you can call $class->method( $values ) or trigger an event to add/get the info to/from the plugin. SIMPLE.

This way you are re-using the code made by the original developers. If you are doing the API with another language code, you just need a bridge class for every plugin. That's it.

But instead of making it the right way, you are trying to remake all the code again, that is a HUGE problem now and it will be a problem in the near future. Some plugins depend of the events fired by the plugins, Eg: On every status update, some plugins add extra info. On every login another event is triggered.
So all you are doing is trying to rebuild all the oxwall software just in another language.
This is what I would do If I were you:

1.- Learn PHP

2.- Learn OOP the right way.

3.- Read the original code of every plugin

4.- Start making your own Oxwall API PHP

You should read all of this before continue with your journey:
DRY:

KISS:

SOLID:

I hope you decide to continue the right way.

Anyways, all the info that you need is contained in the files inside BOL folder of each plugin, it contains all the SQL sentenses, it is a lot of code, so adding it into a post it is not posible.