Need help establishing (hopefully) fool-proof parental controls

[area11]

My 16 yr old son, who has adhd, has thwarted his mom and I at every turn when we try to establish parental controls. Granted, I'm not an android whiz, but I think I know my way around enough to execute a plan if given one.

Ultimately, the kid messages random people - including those of the opposite sex - and while what he types or participates isn't overboard, it's definitely not appropriate.

But flip side of his condition is that we feel he must be within contact at all times.

I've tried to research different apps at different times, but I'm not seeing the one that will accomplish what I want.

So, here are my questions and hopefully viable solution suggestions:

1) I want to physically delete all apps within the base install that can be used for messaging and browsing. Possibly gmail too...Can this be done? I.e., will the OS allow it?

2) I want to put controls on the Play Store so that only an "admin" can download new apps

3) prevent unknown numbers from calling in and restrict dial-out to certain known contacts (parents, family, _some_ friends, 911, etc.)

If anyone can think of other measures I should look into I'm all ears.

Thanks! Jeff