Solo europe trip for 8 months

Hi all, im a 25m, have 60k in non invested savings, a steady 6 figure career in the mines in aus. Started hating my life rhythm, hated being away from friends, loosing connections, loosing hobbies, feeling ehausted, i just overall felt something was off in my life and have decide to quit my job and go traveling.

So ive been over seas once for a 2 week trip to Thailand solo. But I'm thinking I want to go to europe this time for a good 8 months to a year. A good hard reset.

I'm thinking of doing some worldpackers volunteering in between staying in cheap hostels and making my way across europe. Is worldpackers a legit company and if so is it any good and has your experiences with them been good?

Another thing, where is the best place to start? Im looking at setting off in june/july and I was kinda thinking greece and work my way up but not sure, any advice in a path would be much appreciated, I'm just kinda winging it.

How easy is it to make friends in hostels and doing worldpackers volunteering. Do most people go solo, meet people, vibe and then travel with them or are most people just keen to hang out in a destination then say goodbye.

As an Australian do i need visas for every country. Can i use NAB cards over there, is there much use of cash or is it all contactless payments etc.

And lastly is there anything I should know about europe and traveling in general, good places to go, places to avoid things to experience, new things to try etc. Im kinda freaking out tbh.