How to activate DLC without using the launcher

First and Foremost, you should stop playing as a count, it is no longer as straightforward as it used to be. By playing as a weak starting character, you are intentionally handicapping yourself for a game you were completely unprepared for. Try playing as a french duke to begin with. That means that you will have the power of your liege for defensive wars, and can declare war on people much weaker than you, ie rebellious counts and weaker dukes. You should start out only going to war with people who you outnumber by 50 percent, minimum, since you have to deal with seiging and defended bonuses.

You should try not to rely on warfare. Making the right marriage matches and waiting up to an hour for them to come to fruition is part of the game, (playing the long game is part of all paradox games really). In fact, Marriage is actually a much stronger mechanic for taking territory than combat. Not only that, but marriage is the most powerful mechanic in combat as well, because it allows you to call allies with vastly larger militaries than you can command early in the game. An alliance with the king of NearbyNation will let you call in thousands or tens of thousands of additional troops.

Still, the overall point is to stop playing as weak characters. Counts and the occasional 1 province duke in ireland are not advisable start locations for someone unfamiliar with paradox games, because like real life, paradox combat is very swingy. A 20 percent difference in starting numbers can be a 200 percent difference in casualties. That means when starting out, make sure you absolutely have a substantial numerical advantage against whoever you declare war on.

As for your example of losing a battle where you had superior numbers, you probably made a mistake with regards to combat morale, but its difficult to know without screenshots. Even if they had a vastly better general you should not lose a 1000 to 2500 fight, unless you had virtually no morale (probably from not paying the men).

Basic Concepts to Practice:

1. Revoking a county title as a Duke. This usually starts a war of rebellion that you can crush.

2. Invading an independent county as a Duke. This includes ones rebelling from their liege that have become independent temporarily

3. Marrying daughters into a powerful alliance (nearby, but not where you want to expand to)

4. Marrying sons to inherit land

5. Keeping your most important vassals and advisors (particularly the spymaster) happy.

The cause

This is caused by using Windows' text scaling options – specifically, I believe you have yours set to Medium - 125% instead of the default of 100%. I'm guessing that because my launcher looks identical to yours, and text scaling being turned on is why mine looks that way.

The launcher works just fine, but I agree, it's pretty ugly and it bothers me every time I start CKII. It looks like this because the launcher is a phenomenally bad bit of programming and uses explicit pixel locations to place its UI elements, which means it is completely incompatible with the modern scaling methods in Windows 7 and later. It works with Windows XP's text scaling method, which is just to lie to the programs about where the screen's pixels are. In comparison, the Windows 7 and later style of text scaling correctly scales up text without changing the size of a program's windows and buttons. This is a better way to scale UIs, but as you can see, it makes badly-written programs from the XP era, like the launcher, reveal their badly-written-ness.

The solution

Unfortunately, there are only three solutions, all of them annoying.

The first two annoying solutions is to adjust Windows' text and UI scaling options so that the CKII launcher's hardcoded pixel locations line up correctly.

One way of doing this is to enable XP-style text scaling, which is annoying because it will cause all XP-style programs to have unusually large windows and will furthermore make them look blurry, since Windows is doing XP-style lying about the screen's size and pixel locations and just displaying a blown-up image of the windows, giving them that blurry look typical of an image that has been scaled up and smoothed out.

The other way to adjust Windows' text scaling options is to set it back to Smaller - 100% (default) in the Control Panel's Appearance settings. This is annoying because it will make all programs have smaller fonts, which is probably not what you want since you have clearly already chosen Medium (125%). However, if you just chose Medium on a lark and don't actually need the text scaling, then this is the solution for you.

The third way to fix this is the most annoying to do, but the least annoying in the long term, and that is to hand-edit the pixel values in launcher.cfg in your install of CKII. (This is found in your steam folder, in steamapps/common/Crusader Kings II/launcher/.) Fortunately for you, it is incumbent on me to actually edit these numbers in order for this to be a complete answer, so it's only going to be annoying for me – you're just going to be handed a nice text listing that you can cut-and-paste into your own launcher.cfg!

The only lasting annoyingness about this fix is that when CKII is updated or you tell Steam to validate the game cache for CKII, it will notice the change to this file and replace it with the original version. You can reduce the annoyance of this by keeping a backup of the new version so that it's easy to replace after an update or validation.

So here's the listing:

background  = launcher/background.jpg
size            = [ 541, 480 ]
icon            = launcher/logo.ico
text            = "Crusader Kings II"
host            = www.paradoxplaza.com,
dlc_exe         = "ck2.exe",

objects = [
    { 
        "button" = {
            "text"  = "Start CKII" ,
            "pos"   = [ 410 , 370 ] ,
            "size"  = [ 102, 41 ] ,
            "background" = "launcher/button_big.jpg"
            "function" = {
                "type"  = "launch"
                "arg"   = "ck2.exe"
                "mods"  = true
                "post"  = "exit"
            }
        }
    },

    {
        "button" = {
            "text"  = "Register" ,
            "pos"   = [ 410 , 346 ] ,
            "size"  = [ 102, 20 ] ,
            "background" = "launcher/button_small.jpg"
            "function" = {
                "type"  = "link"
                "arg"   = "http://forum.paradoxplaza.com/forum/mygames.php?"
                "external"  = true
            }
        }
    } ,
    {
        "label" = {
            "pos"   = [ 64, 329 ],
            "text"  = "Select mods to play"
            "color" = [ 0, 0, 0 ],
        }
    },

    {
        "label" = {
            "pos"   = [ 272, 329 ],
            "text"  = "Select DLCs"
            "color" = [ 0, 0, 0 ],
        }
    },

    {
        "dlc" = {
            "pos"   = [ 208, 344 ],
            "size"  = [ 192, 80 ],
        }
    },
    {
        "mod_archive" = {
            "pos"   = [ 8, 344 ],
            "size"  = [ 192, 80 ],
        }
    },

    {
        "browser" = {
            "pos"   = [ 0 , 0 ] ,
            "size"  = [ 400, 320 ] ,
            "scroll" = false,
            "url"   = "www.paradoxplaza.com/in-game/ck2/launcher.html",
            "offlineUrl"    = "launcher/launcher.html",
        }
    }
]   

Just make a backup of your launcher.cfg, then open it with a good text editor and paste this into it instead, save, then launch the game. (Make sure the launcher is not running, or it won't let you save the file.) Your launcher should look much nicer now, and as a bonus, it won't have a misplaced apostrophe in "DLCs" anymore: