Another Cooling question

[pilut2]

I have searched, but I still don't completely understand the operation of the coolant tank and the pressure relief valve. My 99 Boxster (39,000 miles second owner) is running great, but burps a little coolant every once and a while. Last year I discovered that my coolant cap was a -01 and seemed to be venting on cool down. I replaced that cap with a genuine Porsche part ending in 04. Since then if my coolant in the tank is anywhere above the minimum level when cold I can randomly lose a bit through the overflow ahead of the right rear wheel, on shutdown at operating temperature. There is no evidence that my tank is leaking. The coolant tank level goes from min to way over max when the car meets operating temperature. Also when the car is at operating temperature the pressure relief valve (not the metal bale on top) is in the open position- is this normal? I cleaned my rads a couple of weekends ago but there was not a significant amount of material to remove. My car seems to run at normal temperatures - the needle will only migrate to the very left side of the 0 in "180" when sitting in traffic. All seems fine if I keep my coolant level at the min level when it is cold- although this does trigger the low coolant light on cooler mornings. I don't seem to be losing any coolant except when I have the odd belch. My water pump is dry, but it will be changed out this summer along with a low temp thermostat, and coolant flush.

In summery my questions are:

1) Is it normal for the coolant to go from min to way over max in the overflow tank when car it at operating temp?
2) Is it normal that the pressure relief valve is in the open position when hot?

Thanks!