investment structure for investment property

We have just bought an investment property for $385K and are looking at different loan structures to maximise our tax break. We currently have our principal residence which has almost been paid off (a nominal amount is outstanding to keep the loan still open).

We are considering the four following options (trying to avoid LMI)

1) pay the 20% deposit and stamp duty out of our own cash reserves, thus eliminating LMI

2) borrow the whole loan amount including stamp duty and cross collaterise the loan with our PPOR.

3) Take out a separate loan of $324K (80%) with the remainder of the loan redrawn from our original loan PPOR. We have been told the whole loan amount is tax deductible, as the redraw is put towards another asset to earn income (almost like redrawing on the loan to buy shares – the interest on the shares loan is tax deductible). We understand that any redraw is not tax deductible if our PPOR became an investment property and earned interest.

4) We also have the option of setting up an offset account attached to an investment loan account, but are unsure how to avoid the MI.
With an offset account, is the whole original interest still deductible and the interest 'earned' from the offset considered taxable income?

Hope anyone can help.