When changeing my oil cooler lines, do I need to take any percaution or some how prime the system before fireing the motor back up?

No, there should be enough left in the cooler to keep oil to the engine on first start-up. Just remember to top off you oil after words.

Have fun; it is a tight squeeze..............

Can anyone tell me how to get the circlips out on the fitting that goes to the block.

The clip in-circles the fitting 3/4 of the way.
You need to find the opening and use a pick to pop it out.
If your going with the same type connector lines I would suggest replacing the 2 fitting's on the block also.
They have been known to fail. It's not worth the chance of blowing off a line for the price of those 2 fittings.

when i changed mine i went with the lube specialist kit which also replaces the cooler. What i did was just unplug my PMD crank for a few times while giving the starter time to cool off. Afterwards I started it and oil pressure built fast enough for me.