Read the thread on the topic. This will give you the best insight on how the program works.
In terms of estimating your income for qualifying for subsidies, line 37 (AGI) is what will determine what subsidies you are eligible for, if any. Print off a few blank copies of the 1040 and start playing around with numbers. Better yet, if you have Turbotax, enter some dummy returns in the software using different scenarios and see how it comes out. If you are within 400% of the poverty level for a family of your size you can still be eligible for subsidies.
Sources of income matter when projecting your AGI. For instance, Roth IRAs are reported when distributed, but are not taxable so do not get carried down to line 37. Assuming capital gains laws don't change, a significant amount of capital gains are excluded from taxable income.
As for the ethics, I'm not sure what you mean there. The important thing is, "Are you honest on your tax returns?" To me that's the ethical question.