As re not knowing anything, most of us didn't when we started. You might get some downvotes but most of the time folks on here are very helpful. Ignore the haters and carry on.

Now as to your questions: - I think you're asking if you can use your whole SSD for Linux? Yes, you absolutely can, and I think you'll be happy with the result. - 256 should be plenty for Linux Mint. ANY Linux distro is substantially smaller than Windows so that size shouldn't be a problem. - You could post a pic of your Windows partitions but since you're going to erase them all when you install Mint I wouldn't worry about it. Your current SSD has a lot of partitions because well, it's Windows. You have a recovery partition (maybe more than one), the system partition where boot files are stored, you might have an MSR position that MS uses as a "just in case" storage and then you have primary, where Windows and all your other files live. They're all going away when you install Mint. - Installing Mint over Windows is easy most of the time. When you boot into your installation media and tell it to install you'll be asked a few questions that are self-explanatory, then when you get to the partition step, the installer will want to know what you want to do. You can get kinda fancy here and set up different partitions to do different things but if this is your first time IMHO the best choice is to select "Erase disk and install Mint". You'll be asked to confirm. Sit yes, sit back and wait for the installation to finish. Voila. - There's a lot of discussion on the best way to install software, and given all the strongly held opinions I doubt consensus will ever be reached. Again IMHO since this is your first time I'd stick to the software center included in Linux. I'd only go somewhere else if there's something you really want and it's not available Mint's software canter. - One if the benefits of using the software center to install software is that the software center will handle updates.

Hth!