1. How do I easily buy this SIA thing? Do they accept credit card? Bank transfer?
Sia developers do not sell Siacoin. You can exchange bitcoin for Siacoin on
http://poloniex.com. You can also buy Siacoin
today at
http://nethut.no with credit card (Visa 3D Secure only), PayPal, bit/altcoins and bank transfer. For now, order have to be place through the
Storage cost estimator at
http://siapulse.com/page/market.
BTW: This vendor is unaffiliated with Nebulous Labs (the Sia developers).
2. Is this a legitimate service or shady "crypto" bullocks? How can I verify their legitimacy?
The developers operate with real names on GitHub, they have their address and location indicated on their Facebook page etc.
3. How do taxes work on this SIA thing?
That depends on your jurisdiction. Presumably, Siacoin would be taxed just like bitcoin in most jurisdictions. Earning Siacoin from hosting storage would be similar to earning bitcoin by mining. Where I'm from (Norway) 25% VAT (domestic sales only) is charged on all cryptocoin sales.
4. What advantage does it give me over traditional cloud storage? (Apart from cost)
Many, but some I think are note-worthy:
Redundancy & geographical decentralization
Built-in encryption (only you have the private key; ask Dropbox, Google Drive etc about that)
Permanent record of file contracts (on the blockchain)
Cryptocoin based (you have bit/altcoin; no need to convert to fiat to buy that storage)
5. Is there a reputation system for hosts? (I'd rather pay a premium than lose data)
I think that's redundant as unreliable hosts are never paid for files they loose, and renters receive a refund (automatically once the file contract expires). Sia also attempts repairs of files when redundancy drops due to hosts going offline (which happens ALL the time). So, loosing your files due to a few bad eggs is unlikely.
6. Where exactly are my files stored? I want to know the identity of the people behind the computers.
The closest you get is geographical localization of IP addresses, unless hosts willingly announce their names/location in some forum:
http://siapulse.com/page/network1. Why is there no "dropping" folder? Other services always offer this.
Sia developers are (rightly so) focusing on core features of the Sia protocol, such as renting/hosting/renewals etc. A "drop-folder" feature could be (in fact: are) developed by 3rd parties today using the Sia AP.
2. How about file versioning. Is every file always backed up?
There is no versioning built into Sia. As of today, you would have to re-upload the entire file if it changes.
4. Can I automatically top-up my account with new SIA every month?
Not yet. Possibilities are that a direct seller of Siacoin top-up your balance using a stored credit card, or that you build your own tools to automatically exchange BTC for SC on Poloniex.