1. You can learn both parallely. DSA helps you build problem solving skills while learning frontend you can get hired immediately, majority of software companies test very basic DSA skills.

2. I suggest with Python or Java if you wanted to attend interviews in Amazon, Google etc. But for Uber, Flipkart etc you can attend DSA in JavaScript as well, as they have lot of frontend positions. Having good knowlegde of two languages is really beneficial, I suggest one backend heavy and frontend heavy language (JavaScript)

3. Freecodecamp.org, Udemy courses,

4. Every interview depends on the position you are interviewing for, in generic software engineering roles its usually only DSA and System Design.

5. IMHO I don't see it yet. Frontend involves lot of customization and integration. Its not about a websites anymore, its web apps and native apps.

6. Networking is always good to place yourself ahead. But dont do it too much that it hinders your productivity