No - the valuation I put in was that of today (A$127.8m market...

No - the valuation I put in was that of today (A$127.8m market Cap) Toro Energy is (today) $106.4 and they are (at this site 0.99%). Details of the fund components are here.
The way ETF work is (as I said) on a pro rata basis of the market cap of each stock on the index as a proportion of the whole index (in this case the Solactive index). To find out more about ETF operation see the following link.
Sure the ETF will have administration functions to receive the money on purchases and repatriate on sales. They will also need to administer the ETF in terms of board (probably for many ETF's) and pay taxes etc. this is where the MER's go. Regarding purchasing and selling of the underlying stocks they are NOT active funds (as are mutual funds) and follow a simple pro-rata rule which is calculated at the end of the day by a computer that set the sales (or purchases) for the next morning., which it then executes (that's why they are so much cheaper in terms of MER). If their is a run (other than from the ETF) and the price responds upward then the pro rata ratio for that stock will increase and the computer will buy more. Likewise if other SH's sell down and the SP drops the computer will sell shares. If the SP stays the same and more funds flow into the ETF they will also buy more (likewise if funds are withdrawn they will sell shares). There is no decision (by the ETF) on the shares they buy or sell this is dictated by the Solactive index. The reason SLX is on this index is because there are not many publically quoted companies in the uranium business.