there's nothing wrong with a portfolio comprised solely of VAS + VGS at all. it's a popular combination (VAS + VTS + VEU is another popular mix) amongst the FIRE movement, most of whom would be in their 30s as well, and that's pretty much all they hold - nothing else.
i am a follower of FIRE, but unlike the majority of the movement i don't fully rely on ETFs. i do hold IVV + VEU for international exposure to help mitigate home bias, but like many here i take direct positions in ASX securities (i trade options on the ASX as well) rather than rely on an index ETF for my Aust exposure.
if you want to trade more frequently (or throw little bits of cash here and there as you say) you're going to want a more competitive broker than the rip-off local brokers. i use IB and am quite happy with the service i get from them, but people seem to like SelfWealth as well. you could read thru the brokers forum for some ideas there.
if you don't want to buy individual stocks and would rather use an ETF for Aust exposure, an alternative to VAS you could consider is the Betashares offering (A200). it has half the MER (0.07% vs VAS 0.14%) and is still based on the ASX200, but they use a slightly different index provider (not S&P) which probably explains the lower MER.