Yeah that tracks - One quick diagnostic: switch to Live View and focus there - if that nails focus while the viewfinder AF misses and it’s a PDAF calibration issue. If your lens has a focus limiter, set it to the likely distance range to cut hunting, and pull off any front filter that might be lowering contrast. In a pinch, a quick blip from your phone’s flashlight to lock focus, then release and shoot, works surprisingly well in dim rooms.
Set your pump to the pressure your board calls for and... it is usually printed by the valve or in the manual. Most all around boards are happy around 12 to 15 PSI, never go over the max. Make sure the valve pin is up so the valve is closed, then thread the hose on snugly. Start the pump and let it run. It will blow fast at first then switch to a higher pressure mode as it nears the target. If your pump has auto shutoff it will stop on its own. If not, watch the gauge and stop at the number. A firm thumb press near the tail should barely give when you are there. Valve pin up.