Unlike what some of the answers and comments state, there is a reason why one could include a slur within a slur (1.1). In jazz, it is common to combine "licks" into slurred sections. I play tenor saxophone and frequently encounter passages like that (one example that comes to mind is the Pink Panther theme). According to my teacher, it means that the first note within the sub-slur is slightly accented (through staccato-legato tonguing or a slight embouchure change).
1.2 looks wrong to me, but I can see how it could be used as well. If I were to see something like that, I would put more emphasis on C compared to 1.1 (in the case of saxophone, I would clearly tongue the note instead of doing staccato-legato tonguing or adjusting the embouchure).
2.1, 2.2 and 2.3 are all valid, depending on the intended message. In 2.1, the first C is sustained and the second is played for 1/4 of the bar. In 2.2, the first C is played for 1/4 of the bar and the second one is sustained. In 2.3, both C's are sustained at the discretion of the performer/conductor.