If you are having a hard time seeing the image please make sure the lens is opened up fully. Yes I know you know to do that, but with all the other things you are thinking about..... A dark cloth is necessary in anything but brilliant light, when the focusing hood is adequate, so if you don't have one you aren't really missing anything. I use a XXXL heavy cotton black tee-shirt I got from Ebay at a tiny tiny fraction of the price of a custom made dark cloth, and the elastic neck hole can be put around the camera body to keep it in place. I use one of Steve Hopf's excellent ground glass screens with my MPP MkVIII, and measuring the standard with the replacement get another stop of light. His screens can be ordered direct or via Ebay. And as others have said, a fresnel will be brighter by maybe two stops over the standard screen.
Your shutter does have a separate mechanism for 1/400th and it will be stiffer enagaging it, so that is normal. Sometimes a sticky shutter can be activated again by carefully opening it up and swabbing the old grease out with naphtha (lighter fuel), but only try this if your feel confident in your abilities. Otherwise a repair man should treat it as an easy job.