In v1.2.0, Sia will implement a host Proof of Burn mechanism in which hosts have to burn certain siacoins to show that they are real and sincere for business to counter the sybil attack. When Sia network is getting mature, the estimate annual burned siacoins can be 0.1% to 0.5% of total available siacoins. The burned siacoins will offset the inflation in the long run. At some point, it could result in a deflation of siacoins.
It's a known problems with the Sia wallet. Once it has too many transaction inputs in the wallet database it chokes and can't send large transactions anymore. The Devs are currently working on solving this and it should be fixed in the next release (1.1.0).
Someone from shapeshift also just joined the slack to ask what's up with the wallet. They're a lot more responsive than the poloniex staff 😀
If I buy a MineBox (https://minebox.io/) would it be doing the automatic maintenance? Or do you still have to manually control the state of your backups?
I believe Minebox will take care it for you through its interface and communication with you. I think Mionebox will make everything user friendly and hide all its integration with Sia platform from the users (maybe except the Siacoins).