I'll do 2-4 because 1 is being researched.
2 - the available portals are for use and work fine, however each has a different XML set up to show the different connection methods. As long as you set the XML how you want, all portals will work the same.
3 - I've heard that, but haven't experienced it myself. I might see if sphereii can push the teleport spot like .5 forward.
4 - you will likely have to add them to loot or make a recipe, I don't recall doing either. Remember, the mod is really for other modders to incorporate, I hadn't realized users would take the time to use them.
I've put in a request to sphereii for a spawnoffset XML property for #3.