For UQ dent, you need an equivalent to OP1 which is usually an ENTER of 99+, however this fluctuates from year to year.
However, just starting from this year UQ has implemented a new scheme where you get 'bonus' points added to your OP rank if you've done a language or spesh(dunno?). Not sure about the finer details, so check it up yourself. This is why people with ENTERs lower than 99 have gotten in this year.
As UQ does not distinguish between people with higher ENTERs but the same OP, once you satisfy the OP1 requirement, your ENTER will not be used in your final ranking for UQ dent. So the only thing distinguishing applicants is UMAT as there is no interview component. Therefore, your UMAT must be fairly high, above 95%tile at least I'd guess.
On UMAT scores, there are several scores provided when you receive your results. Each section of the UMAT is given a score according to how well you performed, and an overall score is provided for your overall performance in the UMAT as well as the percentile that this overall score represents. It is up to the discretion of each uni to use these scores in the way they want.
Here, the 61 in reference to Monash is the overall score, whereas the 170 in reference to UQ is the sum of the individual section scores. That tells you the different ways these two unis use the scores. Btw, the figure of 170 is probably inaccurate for this year due to the change in the bonus points scheme.