They were on iOS before Android, but yeah, smartphone only ATM I think you meant. They are working on a web platform as well, no timeline on when it's ready, just hinted at sometime 2016.
Should be language agnostic assuming a Restful service. I remember seeing some projects pop up on github a few months back from people who got access.
I agree though, some non-mobile options would be nice.
They do have an API, it's one of the ways they plan on making money; just a work in progress at this point.
https://support.robinhood.com/hc/en-us/articles/203585145-Robinhood-API
http://blog.robinhood.com/news/2015/11/20/new-integrations
Does that matter with limit orders though? If I know what price I'm willing to pay for stock X and set my limit buy; I either get it at that price or I don't.
That has nothing to do with Robinhood or fees though. Most people will lose money on any platform. RH just allows you to lose less (no min balance), and at a slower pace (no fees to eat away at your balance).