I think there is a misconception with the word 'transfer' - transferring actually means you can move over results from your law subjects at UTS and make them useable to graduate from your medicine degree at a different university. This is not the case for medicine, as obviously it has very different requirements to other degrees (that being said, if you were to go medicine at UNSW, you need to do 12 UoC (essentially, two courses) of General Education courses and you COULD use your law credits from UTS, but I'm not 100% how that works and you should enquire about this if you do get in).
That aside, of course you can REAPPLY again as a first year undergraduate even after a year at UTS. You will need to sit the UMAT again and apply for universities via UAC. You can also reapply as a first year undergraduate for medicine regardless of how many years of university you have done - as long as you apply through UAC and re-sit the UMAT.
You can do the GAMSAT on the second last year of your undergraduate degree (e.g. second year of commerce).
I would suggest sitting for the UMAT this year and reapplying for undergraduate medicine and seeing how you go. Personally, I don't think it matters if you pick science subjects or not, as if you get in they will teach everyone from foundations anyway. That being said, I have done the UMAT three times before actually getting a good result (2012 - 83, 2013 - 83, 2014 - 99), and I HIGHLY attribute this to doing medical science courses at UNSW. I was exposed to a lot of scientific literature and learnt how to critically analyse and understand large amounts of information, so my section 1 improved dramatically. That's just my personal experience