Answer 1

Picking a language to start learning for app development really all comes down to what platform or device you want it on.

On IOS devices, Swift is a popular choice for development alongside XCode. However, you will need a Mac to start using it. If you want to start using it, I would recommend checking out the Sololearn course for it, as it goes over a lot of aspects of app development w/ XCode, and can really help you understand the process of creating an application (here's a link to it - https://www.sololearn.com/Course/Swift/?ref=app).

For Android development, you have two options (well, technically there are more than two but these are just the more popular choices). The first option is to develop with Java, although it may be a little hard to get the hang of. It is a good language to know for Android development as it's code works for all platforms, so I would recommend using it. The second language is Kotlin, a new-ish language that is extremely popular right now. It is very similar to Java, with its syntax and libraries remaining quite similar, but it does allow for an easier code to read and write and a lot of people seem to be using it now. The one problem that I have with it though is that because it is quite a new language, there aren't too many tutorials or websites online that explain it that well as languages like Java and C++ have, so it may be a little more difficult to learn. Whatever the case, both of these languages are used alongside Android Studio, which allows for the development of applications for nearly all Android devices. Sololearn does offer a tutorial for Java, but it only goes over the language and not Android Studio, so you would have to learn that on your own. They are also working on a Kotlin course, but it is still being developed so it isn't exactly very useful right now (here's a link to the Java course - https://www.sololearn.com/Course/Java/?ref=app).

Hope this helped!