let me try and answer these:
1-Does CBP ever allow the sensor guys to fly, provided they are licensed pilots?
yes they will fly a cessna 206 or astar.
2-Coming from a UAS background, I know full well the weather limitations on the UAS, so my question is what do CBP agents do on non flying days?
collateral duties, go fly manned aircraft or patrol with USBP
3-I'm still waiting on my final official job offer, and I don't know when I would be attending the CBP academy.
about 3-4 months