is -10 oil cooler lines good enough for my 555cui engines or should i step up to -12

Yup it's gonna be squeezed down at the fitting either way and 12 is harder to run. You are talking about the oil lines to the cooler right?

If you need to buy hose and fittings buy from here it's the best place to buy from they have the cheapest price I run -12
http://www.aeroquip.cc/aeroquipracefittings.aspx

from the oil adapter to the oil cooler and then to the remote oil filter housing and the cooler gets plumbed in on the in side correct not after the filter housing

I like filtering the oil before the cooler.

+1,,before it distroys the cooler if the engine xplodes

+2.
Not only that, hot oil filters quicker than cooler oil.
#10 is fine. That's what I use.
Eddie