A. I’m always doing something = perhaps too often, or more often than normal.
A1. I always do (something) = I do it every time
B. think means believe or have an opinion, we do not use the Continuous
B1. think means consider, the continuous is possible
C. He’s being = He’s behaving/ He’s acting
C1. use ‘am/ is/ are’ being to say how somebody is behaving.
D. We normally use the Present Simple (not continuous) with: see, hear, smell, taste
D1. often use ‘can’ + see/ hear/ smell/ taste (e.g. I can hear a strange noise)
D2. can use the Present Simple and Continuous to say how somebody looks of feels now: look, feel.