1. Yes; you do it in layer mode by assigning the two patches to play on different parts of the keyboard (setting the upper and lower limits of each's range). There are already some preset performances that let you do that. You can "look under the hood" (into the edit screens) of those performances to see how they're set up.
2. Yes; again, you do it in layer mode, but this time the key ranges of the two patches overlap. And again, some of the performances are already set up like that. See the back of your manual at the performance lists and look for "Layer" as the perf. type.
3. You can apply any insert EFX and any chorus and reverb to any patch. The preset patches have EFX + chorus + reverb already assigned, but you can change the type and the settings for each and then save your own edits as part of the patch in a user location.
All these procedures are explained in the manual. Sorta.