Google forms are ace. We're about to start using them. It's just a very easy way to create a form which then populates a Google spreadsheet. Previously, I've created HTML forms and validated them on the server with classic ASP, and used them to populate an SQL Server database - which isn't trivial (compared with using Google at least). There are various add-ons you can use with Google forms, I believe, but haven't delved into that so far. I don't know why Microsoft don't offer something similar with Office365.
The biggest stumbling block with Google forms is that, as far as I'm aware, you can't remove Google's branding. I wouldn't want Google's logo to be the first thing our visitors see. So it's not an option for this particular project.
The iPad app I'm looking at has the SMS sent from the app providers servers. You don't configure anything yourself. You just upload a CSV of mobile numbers via their website and they take care of the rest.