Hi ezg97,
I feel overwhelmed by your kind words! Thank you so much!
I am more than happy to help, however I don´t know to which extent my experience can help you as I have almost zero web development knowledge and I am not by any means an expert in game making. Going point by point:
1) It took me about 7 months to complete the game, but I have only spent a few hours per week in my free time the first months, then during the lockdown in my country I was able to spend a few hours each day. I would say that if I had worked on it full time it would have took me about 2 months.
2)This is my second "serious" or full game, you my try "Kyrie Eleison", a platformer that I published a few years ago also in itchio if you feel like it. However I have being creating crappy games that I never finished for about 20 years. It may seem a lot, but it was only as a side-hobby and for fun. I also made a Castlevania fangame, but was never published online.
3)This is a difficult question, I don´t think there is any "holy-grail" resource for game making but experience. I think the best way is starting making crap games and programs and building up from there. This is like playing an instrument, don´t look for magic recipes, just play and play until it sounds good. Learning a programming language (Visual Basic when I was a kid) was what helped me the most, also some maths can be very helpful, long ago I spent a lot of time trying to make an object orbit around another one until I figured out that it was extremely easy with some basic trigonometry.
4) I have never made a game from scratch (except a simple puzzle in Basic), I always used game making software. This particular game was made in Construct3, this kind of software do all the heavy stuff for you, so you only have to focus in programming the game logic (Construct uses visual scripting but you have to program the logic anyway). When you export the game you get a zip file that you only have to embed in the web you want. Other software I like is GameMakerStudio2 (although it needs a separate license for web export) and Pico8 (very cool if you like retro-looking games). Each of them have their pros and their cons. Starting from scratch will take you tons of time just to properly render the graphics, setup collisions, etc...
5) My workflow is usually quite chaotic :D I start by developing an idea in my head for some time, then I sketch something on paper (in this case I drew the house and the house map and wrote down some of the key events) and start drawing the sprites and tileset (I use Aseprite for that). Next (or at the same time) I create all the mechanics (movement, object interaction, functions for handling events, text boxes, save system, dictionaries, visual effects, etc..). Finally I put everything together and design the maps and events of the story.
6)My advise (that you may have heard before) is: Start with something very small and simple. Even a small game can get overwhelming at some point and many many people (inclusding myself) end up abandoning the project because it grows too much.
I hope this helps you at least a little ;)
Thank you again!