Anyone has experience fitting Ionic with Express and/or Socket?

Hi guys,

Wondering if anyone has Ionic together with Express and/or Socket?

I have 3 main queries. Sorry if my queries are odd, my understanding of backend is still poor.

Firstly is since both Express and Socket are web frameworks or for web related developments, do they and can they work in mobile apps?

Secondly, on the point of backend, I understand that socket has its own form of communicating with the backend like socket.on or broadcast etc via Node.js. In that case, wouldnt it render Express redundant since what Express is to enable creation of web API? or are they actually complementary and socket is able to do http requests too?

Thirdly, apart from the pros and cons of SQL vs NoSQL, what I wish to know is your experience handling the DB on a day to day basis. I intend to hook up MongoDB (with understanding it might be less stable than SQL) but its something Im more familiar with.

Last but not least, appreciate any suggestions if my path is wrong or if theres better alternatives.