Hello!
Firstly:
a) if you don't get a med offer this year, then yes, definitely. There are only really a few people who can say something definitely (rather than ability) affected their score and this is absolutely something you can rectify if you sit again. Others can also improve their scores, but it's much easier to do so when there is a concrete thing you know you can do differently!
b) If you start physio in 2020, then no, you can't apply as a school leaver as you won't be a school leaver! Haha. You will be a non-standard applicant with a tertiary record. You would be eligible to apply to JMP, JCU, WSU, UNSW, and Bond. If you accept, but defer, your physio offer, then you would be treated as a gap year student and be eligible to apply everywhere except UQ on the basis of your ATAR. There are pros and cons to this that really only you can answer (ie. what else would you do with your year, etc).
I have no idea about your Secondly section, sorry.
Crow will likely be able to help.
Other: Have you applied to the WA unis and UTAS? Your 88 may well be competitive for them coupled with a 99+ ATAR if that's what you end up with. UTAS in particular is a big unknown for 2020 entry.