Apps on the steem Blockchain?! Questions regarding steem blockchain.

So I get that steemit is just one use of the steem Blockchain and that the steem Blockchain can be used in a multiple of ways.
So my questions are:

If I build a social media app for example Instagram would I be able to link my app to the steem blockchain so that my users can get rewarded for upvotes on their posts?!
If extra features are implemented like stories or live chat could a feature be added so that a user watching the live stream could donate his steem to the creator of the live stream?!
Another feature I interested in is the possibility of having a monthly pledge to my favorite content creator for example?!
If I want to start developing on the steem blockchain where should I start and What prior knowledge or language should I have?!
It would be appreciated if you can help answer the questions above. Thanks for taking your time and reading this post. Have a great day.😊