7D will show up ANY flaws in technique or lens at 100%.
The 50/1.8 is soft at 1.8, it gets good by 2.5.
I had to dial mine in to about +3 or +4 MA to get it to focus spot on, and I have more 'luck' with it when I use spot focusing and use the right focus point (no focus and recompose).
As for shutter speeds, 2 * focal length is a better guestimate for sharp pics unless your technique is great (or you get lucky).
Remember crop factor of 1.6 + super high density sensor.