The LLC is a pass through entity and will show up on your personal Schedule E and once the property shows up on the LLC, the debt (that probably won't show on your personal credit report) will be included in your total debt. 

You should consider using a business name and place your home in the same entity as that business name.

Is your deed holder entity being named as additional insured under GC and sub contractor's policies?

Changing ownership interest percentages shouldn't require changing the name of the entity.  

Regarding number one, while it may or may not be legally necessary (not sure), I think it's a good idea to have a separate account for each entity.

If I do this, will IRS (or any other government entity) start looking at me and wondering what's going on?

An attorney would be able to advise on risk mitigation via insurance vs an entity + commercial loan.

Entities are primarily used for protection from liability.  

You can buy part of a note or perhaps a small note through corporate entities, crowd funding, 506 entities under SEC, but guess what, the SEC only authorizes the formation and operation of pooling investors, these set ups absolutely do not give license to sell or trade stocks, bonds, mutual funds or mortgages as a broker dealer, those requirements are in addition to the pooling of funds authorizations.

Keep in mind that you'll need to qualify full doc (DTI, employment history and income will all come into play) and the property typically needs to be titled to yur personal name, not an entity.