I can't offer any help with the noise I'm afraid.
The oil pressure does increase with the revs and drop again when you take your foot off the gas.
However, once warm the lowest my DE will drop to is a touch under the 1/4 marker.
I'm also quite sure running with too much oil is not good.
To get an accurate oil reading it's best to leave the car for several hours or overnight.
If I remember correctly from L to H on the dipstick is almost a litre.
Hope everything works out.