As always, only a L can advise you on how you might best deal with the business situation in regards to the law.
A business consultant or accountant will often advise a prospective business owner to incorporate if there is a specific need, often revolving around taxes or liability concerns. In regards to liabilities, the reason to incorporate is that while in Canada, the stakeholders have some liability, depending on the concern, generally speaking, a stakeholder is only liable for their portion of the business (generally as a percentage). And further, a business consultant is likely to advise that the business nor other stakeholders are likely to be liable for the debt or liabilities of other stakeholders. So in the event that another stakeholder were to be sued for what ever reason, say it was a divorce, that the business itself would likely be clear of any claim by the stakeholders estranged spouse and that only things like dividend payouts, wages or similar such payments to that stakeholder would likely be able to be claimed against. Operational dollars and corporate assets would likely be free and clear, even if that stakeholder being sued were using it for the purposes of business.
Only a L could advise you specifically about how the courts and legal system would deal with such a situation.
Personally, I would still choose number 4, wfm. Because I would feel comfortable knowing that both my loan and wages would likely be taken care of in the event that a decision to disband or dissolve the business were made. Although I would would personally keep an eye on the business, and might decide at some future date to make a request to have the loan and wages paid out, so I might use that money elsewhere.
Of course, all of the above is simply my own opinion and any choices you make are entirely yours and any legal advice SHOULD be sought by a L as only they can properly advise you in that regard.
