When iOS 10 will be launched or released

Technically speaking, iOS 10 is out already for the developers. The regular users will not be able to use it as yet.
Apple has planned a staggered release schedule as usual. First of all it will be out - in fact, it is already out - for the app developers. A public beta has been scheduled for July. If you want to be one of the public beta testers, you may enroll when the programme is launched. The official release will be two months later. So you may get the official update sometime in September, 2016. The exact date of release has not yet been communicated.

As for the compatibility - all the devices upwards from iPhone 5 will get the next iteration of iOS. The complete list includes -

iPhones
1. iPhone 6s
2. iPhone 6s Plus
3. iPhone 6
4. iPhone 6 Plus
5. iPhone SE
6. iPhone 5S
7. iPhone 5C
8. iPhone 5

iPads

1. iPad Pro 12.9-inch
2. iPad Pro 9.7-inch
3. iPad Air 2
4. iPad Air
5. iPad 4th generation
6. iPad with Retina Display (3rd Gen)
7. iPad 2
8. iPad Mini 4
9. iPad Mini 3
10. iPad Mini 2
11. iPad Mini

iPods

1. iPod Touch 5th-generation
2. iPod Touch 6th-generation

Please note that iPhone 4 and lower models, iPod fourth gen and the original iPad will not get the update iOS 10.

The new update will bring many new features to your iPhone. Some of them are
1. Better lockscreen notifications

2. Decluttered control center

3. 3D touch shortcuts

4. Siri and other Siri based third party apps.

5. Better Apple maps.

IOS 10 is the latest software update by apple announced at WWDC conference earlier this week. IOS 10 has some great features like enhanced user experience, redesign, more control to SIRI, enabling quick type , no more slide to unlock they will be replacing it by touching home button options and many more.

IOS 10 is already available to developers and they are testing it out. For this, you need to have a developer account. But Apple will be opening a program in July where they will allow all the users to test the beta version but make sure before downloading it, as it is beta version it may consists of bugs and make screw your device.

You can wait till September for a free update where they will be releasing it officially along with the new MacBook & I phone devices. This 3-4 months delay is usual, as they want to test it out with developers who are ready to test beta version and give feedback to them of any bugs or improvements rather than releasing it directly. so it's better to wait until September.

IOS 10 will be releasing to following devices

IPad 4 , iPad Air, iPad Air 2, iPad Pro (9.7in and 12.9in) and also to
iPad mini 2 and later iPad mini 2, iPad mini 3, iPad mini 4

iPod touch 6th generation

iPhone 5, iPhone 5, iPhone 5c, iPhone 5s, iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE

As you can see your devices iPhone 5S/5C is listed above, so yes there will be a free upgrade to your device.

Apple will be releasing the iOS with the help of the carrier networks OTA update. So in US the update will be starting based on carrier priority for locked phones. US buyers may get the update from August last week onwards. In India, this release may arrive after 2nd week of September for the locked phones. It could arrive earlier if the mobile operators roll out the updates in their servers. For those enrolled in Apple developer program, they can get the stable updates and patches to the iOS same day from WWDC release.

The iOS10 update released for the developers is not final release. And the update has bugs and still in beta. So apple is taking feedback on the bugs before finally rolling out the update before the new phone release.

Following smartphones will accept new iOS 10 update - iPhone 5 and later (iPhone 5, iPhone 5c, iPhone 5s, iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE). So yes, 5/5S/5C series is going to get the notice for update once the update available for the network.

Apart from phone, here are some devices that will accept the new iphone iOS 10 update - iPad 4 series ( iPad 4, iPad Air, iPad Air 2, iPad Pro), iPad mini 2 and later (iPad mini 2, iPad mini 3, iPad mini 4), iPod touch 6th gen. iPod Pro 4th generation devices are discontinued from this update. So last update is last of their life-cycle.