I think you have a misunderstanding of US tax law, you don't become resident for being there for 30 days. The physical presence test is a secondary test, the test you use is the "bona-fide resident" test and clearly if you are a Canadian citizen with residential ties to Canada, you are a resident of Canada, not the US. You can basically visit for as long as you like provided you maintain ties to Canada, although I have to say I wouldn't try pushing it too far (say beyond six months a year and you can't stay longer than that as a Canadian visitor anyway). You don't deduct days from the $87,600 cap where you were a bona-fide resident abroad, that is only really used if you move your tax home to the US, which you're not going to do, you would benefit from the full limit even if you spend time in the US as a visitor.
If you're self-employed in Canada that has no bearing on your filing status in the US, they don't care. You have your T4 and your T5s, you use that to complete your 1040 and do an exchange rate conversion. If your income is less than US$87,600 then you can use Form 2555-EZ which is pretty easy to fill in. Basically on your 1040 your income should show as zero once you've worked it out, if your income is below the cap.
Might take you an hour or two the first time you do it but it's not hard. Not as hard as renouncing citizenship at any rate. Basically you're just putting your name and address on a 1040 with "zero" at the bottom and declaring your foreign income to the IRS on the 2555.
If you were a resident of the US you would actually be in a better situation tax-wise than being non-resident, because you could claim a foreign tax credit for any amount as there is no cap for residents and you would file as a non-resident in Canada. You'd still pay the same amount of tax as the Canadian rates are higher. Frankly this is the way a lot of Americans get around the cap. Then you would need to use Form 1116.
Like I said above, the only reason to renounce citizenship is if your income is above $87,600 a year.
If you're having a problem remembering the exact dates those aren't really important unless you were in the US on a business trip (earning money), or you were subject to the physical presence test, neither of which apply to you. Just put your best guess down on the form, it has no real bearing on how much tax you pay.
The only other form you might need is 8891, which is for declaring RRSPs. Distributions inside RRSPs are no longer subject to income tax in the US under the 2008 tax treaty, it's just a declaration basically although income taken from them would be part of your income obviously. You also have to report your financial assets abroad worth more than $10,000 on the FinCEN FBAR form, but that's not a tax form.
http://www.fincen.gov/forms/files/f9022-1_fbar.pdf
Steve.