About emoji keyboard, Android has one included. Just keep pressed the bottom right button (the green one) and the option shows. Then move your finger to the left while still touching the screen.
But Android’s emojis are not those you are used to: i.e. the Apple ones. You can change them with root access (which FPOS-OS has embedded) with the help of a tool such as Emoji Switcher. I opted for EmojiOne, but I installed them manually, not through Emoji Switcher.