Hi Sreedevi,
1. S32 Design Studio is newer one, it's successor of CodeWarrior. My recommendation is to use S32DS because it's free of charge. There are no restrictions.
2. Yes, the code can be ported to S32DS. I can't see problem here.
3. Can you see this folder?
c:\Program Files (x86)\Freescale\MPC56xxSLibsV2_0R46\MPC56xxSLibsV2_0R46\Doc\
The labs are explained here:
c:\Program Files (x86)\Freescale\MPC56xxSLibsV2_0R46\MPC56xxSLibsV2_0R46\Doc\labs\Labs.pdf
And there are other useful documents.
Regards,
Lukas