I can't speak specifically for AVL nor am I giving any advice...

I can't speak specifically for AVL nor am I giving any advice but it should be straight forward. Pay your money to the comp and they convert the oppies to shares which are then shown in your holdings generally about 2 weeks turnaround but that time differs for each company. Once its done AVL will issue a notice for option conversion via asx.

I haven't heard anyone having security issues. In a way the process re security is similar to paying a bill via bpay - it has become standard practice. I guess if you run into issues you can get the transaction reversed through your bank.