As said above, web development is a broad term. There are front-end developers and back-end developers (and then there are designers who just do the mock-ups/graphics/UX work).
Front-end involves everything you see on the page once it is loaded (HTML, CSS, Javascript/JQuery--which is a libary for Javascript that makes a lot of things easier). You could possibly get away with a job somewhere that would only require you to work on HTML and CSS, but you should at least have a basic understanding of how to integrate some JQuery plugins into your websites, and how to customize them using JSON (if they're quality plugins, they should have those options available). HTML and CSS are constantly evolving in that they can do a lot of things that otherwise were limited to using a programming language like JS, so you will probably see a lot of examples of cool-and-new stuff like that, but it's important to know that 99% of it will not work in IE (let alone old versions of IE), so from an accessibility stand-point, avoid having to depend on those functions to make your website usable. Jobs in this section will also commonly ask you to be familiar with frameworks like Bootstrap, but I personally prefer to do as much as I can from scratch because I like to have full control (and because last I've looked, Bootstrap tends to uses floats for their structure, which is
bad). Up to you, but do be aware of it if you are looking for a job in the future.
Back-end involves the programming that is processed by a server before the page is loaded (PHP being the most common in my experience, followed by ASP although my father will swear by Ruby/Ruby on Rails and a friend of mine believes Go will eventually usurp PHP). This generally involves interaction with databases (SQL) and/or other servers, as well as processing forms, user sessions, and other information that needs to be passed between one page and another page.
Template sites like Wordpress are very popular because they make it easy for someone who has primarily front-end experience to create an entire website, as it covers the back-end development for you, including CMS (Content Management System, a portal for clients to log in and submit data to display on their website). You can also customize Wordpress, including the CMS, hence all the templates and plugins that are available to download (some people just make money off of selling these WP tools too). If you are making a website from scratch, either you should know how to work with databases and back-end development, or the website should be static and small enough that the client does not require to regularly maintain the content themselves (or else is ready to pay you to do it for them).
First question is what you enjoy. I started out in front-end when I stumbled into a small start-up that suddenly shifted me from data-entry to things way outside my box, but I happen to love programming, so I decided to delve into back-end instead. My suggestion to decide this is to try making a website from scratch (which, even if you decide to go with something like Wordpress, will help you understand how to work with it). Start just with basic HTML/CSS, try integrating some JQuery plugins (try a lightbox, which you commonly see on websites like FB or Tumblr--I use
http://fancybox.net/). Then you can move onto learning some PHP (or language of your choice) and trying to use that just to set up your own simple "templates." Then eventually you can try to look into databases, but you might want to take a class on that if you are not used to programming logic.
If the answer to the first question is front-end only, then next question is where you want to go with it. If you want to do it for your own clients, then learn to work with Wordpress. If you want a job in the industry, some companies will ask you to work with things like Bootstrap and Wordpress to minimize cost/time for a project. Other companies may use and design their own back-end/CMS, so you'd have a lot more freedom, but you would need to know how to not rely on the aforementioned tools. Now that I think about it, I also wouldn't be surprised if some companies ask back-end developers to be familiar with Wordpress as well and how to build on top of it (again, to save costs).
As for web design trends, my favorite website when I still doing that stuff was
http://tympanus.net/codrops/ for inspiration. My personal aesthetic is flat designs, which, last I heard two years ago, is the going trend (and Codrop's website is an example of such a design). I might be able to find other resources that I used to peruse, but I think most of that was saved on my old work computer, so I'll have to do a bit of research to re-discover them.
If you start getting into things and can't make them work, send me a PM; I happen to love debugging.
Edit: Re-read the posts and wanted to add a few things.
Java != Javascript; they aren't even related, so don't get the two confused. You may have only referred to it as Java as an abbreviation, but I wanted to make sure you didn't start looking into the wrong language.
Yes, Javascript is, relatively speaking, a confusing language (imo, mostly because you have to get used to the idea of working with the DOM). However, you can't compare a scripting language to a markup language like HTML, so don't expect the two to be anything alike. HTML is more like XML and Javascript is more like Lua.
CSS is not "secondary" and "unncessary." It is required for any validated website, unless you want everything to be black and white. Also, don't use any in-line styles unless you're working with Javascript animations.
Newsletters go into marketing, which is fine, but do know that unless you plan to write your own script to send these, people tend to handle newsletters using campaign websites, which will charge a fee (either monthly or per campaign). If you go this route, you should also be aware that there are many restrictions on the code in an e-mail (no refs (everything has to be in-line) and some HTML objects are not allowed). The easy route is to make the whole thing one big image.