Hi Gokul!
All awesome questions for getting started.
1) What will be your suggestion/advice for a beginner in data viz?
Welcome! I would say my biggest suggestion is to learn what SVG elements are and what they do. Without that knowledge, you'll always be fumbling around with other people's visualizations instead of being able to abstract and create your own.
2) Where to start as a data visualization developer?
I would say, work on a variety of small projects to start. It's easy to master one way of working, but at the get, building a lot of smaller things gives you a better sense of the abstractions you are using
3) What will be your recommendation on the learning resources for D3 for beginners apart from the official GitHub docs ;) ?
You should check out Shirley Wu's d3 course on Frontend Masters? She's an excellent teacher, and she does a great job of really honing in on what's important to get you started. I also really loved this O'Reilly book, but I think it's being updated to v4 at this moment:
amazon.com/Interactive-Data-Visualization-Web-Int…
4) SVG or CANVAS? #futurePrespective
SVG and canvas, they both do different things. SVG are vector, so they are really wonderful for building and drawing shapes that are crisp on any display. Canvas are bitmaps, and are really great at a ton of data, or a lot of movement. I reach for each tool separately. Do I need it to be responsive and accessible? SVG. Do I want to make particles fly across the screen? Canvas. This is a generalization, but you get the drift 😉
5) is D3 alone enough for dataWiz?
I think when you're starting out, D3 is just fine. D3 is an incredibly powerful library and it's become synonymous with data visualization for a good reason. Eventually, you'll learn the tools deeply enough that you can start to build it without D3 if you wish, or use other abstractions on top of it. I would, however, suggest learning GreenSock in parallel, because while D3 is great at transitioning some data from one form to another, there are some more sophisticated animation effects and tooling that GreenSock offers that D3 does not, and they play really nicely together.
I hope that helps!