Oil pressure is ok for a std oilpump, but not on a high presure oil pump tho, it looses pressure cause the oil gets to thin so it cant uphold the "normal" idle pressure, this happens when the engine is hot as in just after you have canned it or a hot summerday.
This counts for the hissing in the tank also, as long as the water doesent come out ot the lid itself, your ok
water level on stainless tanks should be; when cold, just under the top big waterhose outlet, and yes, when you have a swirlpot the water comes out of the top small oputlet all the time, this is wery normal