Some basic Steemit questions

1. It is not fixed, you can get realtime data about it on steemstats.com
2. It is fixed at 10% per year apparently.
3. Yes, added each month, though you might have to do something with your SBD after a month for the interest to show. Steemstats also shows what is the expected interest you will get on SBD you hold.
4. Yes you can purchase SBD and transfer them to steemit. If you purchase and transfer STEEM there is no way to directy change it to SBD on steemit, you need to use an exchange service for that. With SBD you can however turn in to STEEM, but there is 1 week waiting time for the conversion... you can do it much faster on an exchange.

@cryptos fantastic, thanks for the great answers!