using LOC to make repayments

Depends on many factors such as the reason for doing this.

Again, would depend on the situation and purpose. Why would you want to structure it that way?

In that case the interest on the LOC would likely NOT be deductible. see:
TD 2011/D8

Income tax: does a taxpayer's purpose of 'paying their home loan off sooner' mean that Part IVA of the Income Tax Assessment Act 1936 cannot apply to an 'investment loan interest payment arrangement' of the type described in this Taxation Determination?
http://law.ato.gov.au/atolaw/view.htm?docid=%22DXT%2FTD2011D8%2FNAT%2FATO%2F00001%22

But, there may still be ways to do what you want to do, so don't give up.

It may also be wise to apply for a private ruling..

The law says that interest in deductible if the funds borrowed are used for investment purposes. The ATO has also confirmed that interest on interest would be deductible where the original borrowings is for investment purposes. But they have said in TD 2011/D8 that they will disallow the deduction on the capitalised interest if the dominant purpose if to pay off your own home loan sooner. They do this under Part IVA of the ITAA 1936 if you are doing something with the dominant purpose of obtaining a deduction.

Therefore, you could be able to claim a deduction if the reason if the dominant purpose was not to claim an extra tax deduction but for other reasons. One reason that may be applicable could be for cashflow.

So in order to be safe if could be a good idea to apply to the ATO for a private ruling, outlining your situation and the reasons for doing this and then asking would the interest on the LOC be deductible?

You can apply for a private ruling by doing it yourself, search the ATO website, or using a tax advisor.