You only need to include csound64.dll*, but you no longer need to include libsndfile. You may have to include some plugin opcode dlls depending on what opcodes you are using, In most cases, all the opcodes you use are in csound64.dll, but in some cases they will be in auxiliary dlls. For example, the fluid opcodes have their own dll. If you use them, you'll also need to include that dll.
With regards to the installer, it's best to simply hack an existing one. You can take a look at the Cabbage installer script, or better again, check out the ToneZ installer script for Windows by @T0NIT0RMX. Just modify the part you need to. Note that you don't need to change anything below line 56. It should be pretty straight forward.
Finally, you will note that @T0NIT0RMX puts all resource files, including the .csd file into a folder called T0NIT0RMX in the ProgramData directory. This means the dll can be placed on its own into the VST folders. If you wish to do this you will need to build Cabbage yourself and modify the manufacturer ID. For now it might be simplest to just bundle everything into a single directory that gets installed to your VST folder.
Let us know if you have any problems.