1/ Does the Novels cover the complete story in detail, or should I start with the codex / codices, or both ?. Any other sources that might be fit for the purpose ?
The novels cover their own story. Maybe not completely but pending what you're interested in reading I think the novels are nice. Also see Lexicanum.
2/ What would be the most appropriate chronological order of reading the books ?
Of which series?
For the Horus Heresy there is a "recommended" plot line, what I don't remember off hand; for others such as Guant's Ghosts they tell you the order.
First up, thank you very much for your time & effort to answer on such short notice
Sadly brother, I don't even know the exact point, where the entity of warhammer began. Vast timeline, so much factions, each with their own starting point.
(a) Some folks say that start with the Legends (Teclis, Tyrion, Malekith.....), then Nagash
followed by Sigmar, Neferata and End Times.
(b) Some say that start with the Rogue Trader & all the rule books.
(c) Some say that find corresponding books from timeline.
This is where I am stuck and heavily confused........ folks at reddit and other 40k Forums won't even answer my questions anymore :/
That being the point, could you please help me with the following :-
1/ Where did the lore actually start ??. Generally, folks take the easy way out by saying Horus Heresy or Legends. Even in Black Library, on the oldest published book by date in any category (Quick Reads / Novels / Novellas) it says "it all begins here" and the same thing pop up in Horus Heresy.
2/ If I have to follow the timeline, is there a guide to help me understand the milleniums so that I can follow up properly ?. Also, is there is external source that point out the books according to the timelines ?
3/ If all else fails, how big of a matter it is, If I start reading randomly ?
Thanks again (P.S -- I hope I am not pissing you off bruh)