RT-AC68U: How much can I run on this thing before it cant cope?

Hi bought this primarily for the vpn capabilities.

I'm on Merlin.

Considering running:
VPN max encryption
Local storage plugged into usb 3
transmission
Adblocker
skynet

and possibly more as I find out about them.

Can this thing cope?

And any other useful tools that i might want to add?

Thanks