Cisco FWSM, Cisco ASA (FW, IPsec, SSLVPN) migration. What are the fundamental changes?

I learned that FG handles session timeout with deifined services on the FG that actually will define the timeout on a per protocol basis, even if a permit any any rule is in place. Where are the exact details about this behavior to be found? What other factors could cause an issue when migrating from Cisco ASA/FWSM to FG in terms of: A) any system, default settings that might affect traffice (TCP normalization and others that could cause issues) B) session helpers that just work without being asked??? FTP FTP_PUT FTP_GET how do they work in detail? C) any other gotchas?