IT freelancing / self-employed, Expenses, Bureaucracy

Hi,
I'm moving to Vienna soon. I'm EU citizen, I've got a hobby for a customer in another EU country - technical support and further development of a website for +/- €1000/year before tax. Due to living in the same country and having a full-time time job I was exempt from paying VAT and generally it was very easy to do the taxes and annual tax reports.

I won't have a job at the beginning, I'd like to keep this hobby, just wondering if I'll have much of that €1000 left after all the taxes and fees. I wish a bookkeeper would sort it out all for me, but that that's even more money towards ZERO.

As far as I understand, I'd need to pay minimum accident insurance just over €100/year or optional voluntary €418/year, no income tax because of under €11000, VAT 20% for exporting digital services, register with WKO (around €100/year or one-time). What else: info online very messy, my German too basic to understand. Anything important I've missed out?
Sorry for so much text, just trying to figure out how to keep doing this little project (very attached to it), I'm sure the customer won't mind paying extra 20% VAT, but all that hassle and extra expenses - big doubts that it's worth it at all.

Your thoughts / similar experiences?
I see a some old answers in forums, just wondering, if maybe there's all the necessary info gathered together already and up to date? Links welcome!

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