At majors it's usually the PM who does all that, except the CA usually does the welcome aboard at the gate. More common for the CA to do all the PA heavy lifting at regionals, but most major pilots were either regional CA's or military officers, and have some experience.

Most airlines have scripts in the manual, these are rigidly enforced for FA's but not enforced at all for pilots. Look at the script in your FOM, use that to inform you to develop your own personal script. Short and to the point, provide key info including likely delays.

Keep in mind that whole *most* pax would just prefer that you STHU, a few nervous travelers are comforted by hearing from a pilot who sounds like he knows what he's doing. I throw in a little more meat than I would otherwise just for them.