Ok, lets split the problem in smaller pieces:
- The form not going into the second page and just showing a + sign: I got that too... the problem is that your box is fixed on size, you have to allow to "Expand to fit" at the "Layout" options for the Textbox

- About the parts that stays on the background on every page and the ones that are only for the page you are inserting it, the problem is that you have to select the "working area" at the "Master Page", so anything that it's outside the purple rectangle would appear on every page, everything that is put inside the purple rectangle it would be only for that page:


Outcome:
