Hello,
I am a new member at this interesting community and i recently bought the 2shpn routerboard and a 15dbi level one omnidirectional antenna for wireless network coverage at a campus where i am working as a software engineer. So i have seted up the anntena to work as ap bridge bat when i se the overal TX CCQ at the 2SHPn the value is 3%. can you please help me how to improve it? the hardware connection is not good? any help would be perfect! Thank You very much!!!

This value will increase once you start transmitting data. Without traffic, CCQ will be low.

Another thing to keep it mind is local interference. I have an idea of what channel I'll use on an AP, but once I get on site I have to tune each one to the location.

You can use the spectral scan to see the local noise or easier and almost as effective is to log into the AP and do a scan or snoop from the wireless interface. You'll see the local traffic and see which channels are clear to use.