Similarly coming from a Java background I personally found Swift quite an easy language to pick up and was a great entrance into native iOS development. Despite how much Apple are pushing Swift, there is still a lot of Objective-C around though so I definitely wouldn't try and shy away from learning it even if it isn't your primary language.
In terms of IDE's your options are really either AppCode or Xcode. Despite being the obvious choice, actually being made by Apple, Xcode is honestly not that good especially for Swift (which again, is their language). Basic refactoring is still not supported and many activities are a bit of a chore and probably cause the IDE to crash. Saying that if you want to use the interface builder then you've pretty much got to use it for some stuff. Whilst swapping between them can be quite laborious, the benefits (such as better debugging, refactoring support, and a better overall experience) mean I'd rather use it for primary development. It's also worth noting that AppCode is not free (which Xcode is).
In terms of a starting point I would probably recommend using (contradicting my previous statement) Xcode's "Playgrounds" feature and just get a feel for the classes and APIs available to you without the daunt of an entire project. Keep it small with a single view, add some text and buttons and see what you can come up with. I also find (whilst milage may vary) that exploring open-source projects and trying to contribute is a great way to see some good (and bad) practices!