If it’s a strata scheme then the owners corporation (aka body corporate) exists by default. The strata committee comprises both owners (or their representatives) although it sounds like they may never have met.
Two-lot strata schemes are different and can be tricky, and I’m not sure about their obligations to hold meetings and issue minutes but I imagine they would be the same as other small schemes (less than 100 lots). Otherwise to answer your questions:
How are the cost of repairs divided?
The costs are divided according to the unit entitlements.
The roof tiles need replacing who pays?
Unless there is something on the strata management plan to say otherwise, the roof is common property and the costs of repairs are decided according to unit entitlements, in this case, 70-30.
Voting rights ?
Same. In this case 70-30 although anything that requires a special resolution would need a unanimous vote
What does the legislation require ?
Much the same as for other strata schemes, except that owners in 2-lot schemes can agree unanimously not to have a maintenance (sinking) fund and not to have collective strata insurance provided they are separate buildings (which would not apply in this case).
There are only 2 by-laws?
In the case of the scheme having no by-laws for specific issues that are covered in the Model By-laws for NSW, the model by-laws would prevail (although they might have to agree on which of the pet by-law models to adopt).
You might find that a lot of disputes in 2-lot strata schemes end up in the Tribunal, especially over issues about repairs and maintenance. One example might be, where the minority owner wants the owners corp to fix common property and the majority owner doesn’t want to pay for it, despite there being statutory duty to do so.
Have a look at Fair Trading’s Strata Living Guide for more information.
The opinions offered in these Forum posts and replies are not intended to be taken as legal advice. Readers with serious issues should consult experienced strata lawyers.