I'm along the way of transforming a CodeIgniter web site to Joomla. The majority of the website is static data and really should make room pretty much. Though, you will find a couple of locations that there exists a handful of workflows, sights from data sources, etc. Considering keeping existing CI pages of these and integrate into Joomla via it's Wrapper iframe control (for the time being).

Is a great way to go (for a while)?

I'm new new at Joomla, so afterwards for full integration, would I create Joomla components?

Not understanding particularly exactly what the submissions are or what it really appears like, it's difficult to say the way you would integrate it later. However, speaking in very general terms, there's a great possibility you could port this content over without needing to write custom extensions by utilizing a variety of CCK components. I'd have a look at individuals methods to try to stay away from iframes if whatsoever possible.