Welcome to the forum David.
Where and what state is Wanilla - you may wish to place that in your profile.
Secondly, there is little in terms of requirements on storm chasing although these days, more and more people are getting the bells and whistles.
Obviously depending on photographic and filming requirements, if not already perhaps purchase a decent camera and video camera. Others on here may wish to share their experience on what models they prefer but there are some threads way back on this anyway. A steady tripod is a must and you will soon learn that unsteady footage makes it difficult to identify rotation in storms and is vital for timelapse.
Most of all, you require a reliable car and know the vehicle. Recently, I was in Canberra for instance (not on a storm chase) and the immobiliser decided to play tricks. This required a full set of instructions on how to reset - the first time it had done this! You would not want this to occur with a violent wedge tornado bearing down on you.
Contacting other chasers can be done on this list. Choosing the right partner is someone with whom you get along with but also at the same time you are able to trust in safety and scientifically (collaboration). Some partners may feed on each other making the partnership dangerous to their understanding of storm dynamics and misreporting. This is why it is essential to read up as much as you can handle on the theoretical component of storm chasing!
This is a brief overview given my time constraints.