Offshoreonly.com - 496Ho, need some help?

I just got the boat all put back together and trying to figure a few things out, boat seem to run good, water temp was around 160 ( did rise up when coming off plane) and oil pressure was around between 20-40 psi.. I dont have a oil temp gauge but wish i had one right about now.. How hot should my oil filter be, when i put my hand on it, it was pretty hot, after a couple of seconds i had to pull my hand away..

I also have some marks on my coolant res. that use to judge the level in my tank, and after this trip i noticed the level was higher, which means either pressure, or sea water, how could i confirm one or the other? Im guessing if it is sea water, that would mean my heat exchanger has a problem?

The last thing im looking into is, again my temp seemed to be good, however at idle i have steam coming out the exhaust, this happens even when i fludh the motor. That to me means the exhaust is alittle to hot, but im not sure how i could improve the water flow anymore?? any thoughts?? ideas