Want to force Word to display a number that's one higher than the real page number? Try using the following field, where braces are inserted using Ctrl/F9:
{ = { PAGE } + 1 }

Want to tell Word to display a page number on pages one, two, and three, but not on any other pages?
{ IF { PAGE } < 4 "{ PAGE }" "" }
Note! Make sure to leave spaces around the < sign.

Want to tell Word to put the real page number on pages one, two, and three, but a higher-by-one page number on all other pages?
{ IF { PAGE } < 4 "{ PAGE }" "{ = { PAGE } + 1 }" }

Want Word to insert Continued... on every page except the final page, where you want it to display - End - instead? Use this:
{IF { PAGE } < { NUMPAGES } "Continued..." "- End -" }