If you open up your Wacom Tablet settings (on the Mac you go Apple menu ▶ System Preferences and then choose the “Wacom Tablet” item) then go to the “Pen” pane and tap “Options …” and you will see a setting called “Handedness” and obviously you want to set it to “Left.”
Other than that, the Wacom Tablet works exactly the same for you as for a right-handed user. The keyboard shortcuts are inconvenient for everyone who uses a pen. That is why most Wacom Tablets have buttons on them. You can program the buttons to the Cut, Copy, Paste keystrokes. That is very common. Another option is to turn on Sticky Keys which enables you to press Command+V by pressing Command and then pressing V. But even so, there will still be times when you want to put down the pen and work the keyboard with both hands. That is why most of the Wacom Tablets come with a little pen holder that you can easily put the pen into and pick it up out of quickly. You won’t necessarily hold the pen 100% of the time as you’re working, same as you don’t hold the mouse 100% of the time.
You shouldn’t have to use a mouse when using a tablet. There is only one mouse cursor, and it is controlled by both the pen and the mouse. You might want to use the scroller on your mouse along with the pen, but in that case, the fact that you have been using a right-handed mouse actually works in your favor because you can have the pen in your left but operate the mouse scroller with your right. But beyond drawing and painting, the pen is actually an awesome mouse. For example, you can do file management tasks in Finder (and I assume, in Windows Explorer) much faster with the pen than with the mouse. You can select menu items in Photoshop or manipulate windows much better with the pen than the mouse. So if you haven’t been doing so, I suggest you just use the pen with your computer 100% of the time and within a few days you may never go back to the mouse. I haven’t used a mouse at all for many, many years. The pen is just so much more accurate and much faster.
Keep in mind that there is an adjustment period where the pen will feel strange to you. It takes a little while to develop the proper hand-eye coordination and muscle memory. But after a short while, the location of common objects you are using like Photoshop tools and system menus will get “into your hands” and it becomes second nature to just reach for them. That is what you are aiming for. But it does take an adjustment period.
Also, keep in mind that even if you are great with pencil-and-paper drawing, that is not what you are doing with a Wacom Tablet. In Photoshop (or another bitmap editor) you are painting. It is more like an airbrush than a pencil. In Illustrator (or another vector drawing app) there is drawing but it is more like calligraphy, and there is also manipulating shapes and nodes with a super-accurate mouse. So again, there is definitely an adjustment period where you will work more slowly and deliberately and it can be frustrating. However, once you get through that adjustment period, you will likely work 5–10x faster than with the mouse, and also do much better work than with a mouse because of the additional control that you have over the tools.