HC-SR501 with LDR attached to it.

This is great....Really....

Now...what I have so far is adjustable Dark range and the Lamp is on ONLY in the dark that I specified though the pot as you suggested.

And yes the lamp goes off after few second. This is great so far.

Now latching the relay and the momentary switch. I like the idea of second relay.But I have no idea how to connect it to latch the lamp on after these few seconds!!!

Also how the momentary switch does the flipping of on/off of the lamp. HOW ?? your explanation will be greatly appreciated.

I will make sure that the PIR is hidden to avoid the retriggering and messing things up.