You can have listed or unlisted options I haven't checked fine detail but presume they will be listed options. If they are they will showup on your comsec holding account. You will have to amend your watch list.
The code depends on whether there are other options as an example THX which own significant stake in UMC has options THXOA
Conversion price. If you own UMC you will be given one option for every share so conversion price is 0 + 1.35. If you can and do buy on market you are correct the price will be what you paid for them place the conversion price.
One thing to be careful off is that if you convert options to shares the the capital gain tax free period for the new shares starts again.
Hope helps
UMC Price at posting:
$1.03 Sentiment: Hold Disclosure: Held