#2
Is that from the don't cry tab? The chorus? If it is, then don't care about the hammer on, just play it like an F. Sounds pretty much the same..
#4
Or play the low 1 on the E string with your thumb, the 3's on the A and D strings with pinky and ring fingers, hammer on the 0 to 2 with your middle finger, and keep your index on the 1 on the b string.