Child support modification question [OR]

I live in Oregon.

I receive child support under an established order in, based on the parenting plan that was agreed on at the divorce (finalized in Feb 2015). For all of 2016, and (so far) 2017 my ex has not been using his parenting time. No overnights, and only casual email/facebook contact. I think he had one or two lunches with her in 2016.

I'm wondering if I can file the forms to request a modification in the child support amount, on the grounds that he has had no overnights, and so the calculation should be redone using a value of 0 overnights.

During this time, he has earned a degree, though I have had no significant contact with him, so I don't know if he has an income. The original calculation was done based on the amount of alimony he is receiving from me (the judge declined to impute minimum wage to him, and instead basically said he should just go to school full time).

As well, over the last couple of years, my own income has increased by almost $2000.

My questions:

1. Does the child support calculation have to rely on the parenting time in the parenting plan? (i.e. will I need to get the parenting plan revised before I can change the child support amount?)

2. Is there a chance that asking for a modification would result in him having to pay less child support (should I let sleeping dogs lie?)

3. What if he has a job and lies about his income? Will the state be able to tell if he's hiding income?

4. Does "he has no overnights" and "he has a degree now but I don't know if he has a job" constitute a significant enough change in circumstances to warrant a revision in the child support order?

5. I can have my child support order reviewed after 35 months, and not have to show a "significant" change in circumstances. What is the start date for this period? I have a letter that says that the payments were ordered to begin in 2014, which was before the divorce was finalized (part of a temporary support order, I think). But my account was established in the computer system in 2015, a couple of months after the divorce was finalized.