The press is at a very slight angle 85 degrees instead of a perfect 90. Will this have an effect on how the powder meters ?
No, Mine isn't mounted on a perfect 90 either, and the powder measure is the most accurate on the three that I have. It's very accurate with powders that meter well. Most of the different brands are. Mine is off about half a bubble from plumb.
With yours being new it will have the same problems all new measures have. Mine was a bit of a pain when it was new but after a couple thousand rounds it settled in and very seldom varies more than .1 of a gr now.
They all very .1 of a grain but most of the scales won't always pick it up because they are + or - .1gr accuracy anyways.
That's why when I post a recipe I usually say 7.3-7.4gr or whatever. That drift is normal with all measures.
Once mine is rolling I get tired of checking it because it is always the same. It mostly will stay at 7.3 but I will find a 7.4 once in a while.
When I start a session I will check every 10 cases for a while and when I know it's settled in I will jump that to every 30 or 40 or when I think about it.
I fill it 2/3 full, set my control panel alarm for 1/3 full and when it goes off I fill it back up to 2/3 full and my load never leave this .1gr range.
I don't use Unique, 800x, Blue dot or any of the other problematic powders in my AP measure.
If I'm using Bluedot or some other brand of cornflakes, I run it through my Auto-Charge or just scale it.
I have no illusions that powder like that will meter to what I consider accurate, through any volumetric measure that I can afford to buy.