First of all, be a wise man and switch Max to Light Color scheme!
Just joking…
Now about the shortcuts. There are several alternative approaches to creating nodes in Magma, and the direct shortcuts do not cover all nodes. Of course it would be nice to have them all listed in the depot, and I might just do that, but dragging from the depot is really the last resort, so I wanted to make sure you are aware of all other methods currently available:
*All Nodes Menu - Just right-click anywhere in the editor and select Create Nodes Menu… - this will give you the depot content in a form that is faster to navigate, and no dragging&dropping and long mouse moves are necessary.
*Depot Menus: The first letter of the Depot Categories (except for Trigonometry where it is the second because Transform has already used T) pop up a menu with that category’s nodes under the mouse cursor. Then the name of the node is underlined, so you know what letter to click. This is what we call a multi-stroke shortcuts. E.g. you can press F for function and C for Clamp, so the shortcut is F>C. To create an Input Channel Position, you can do I>C>P and so on. At some point the sequences will become second nature because some of them are very logical (for example A>D does Add, A>B does Abs etc.), or because they are kinda funny (F>U does Function>cUrve) 
*Dragging From Sockets: Once you have a node, you can drag from its Input or Output sockets to either create nodes automagically, or show a menu with all or a few nodes that make sense. For example, pressing O>N to make an Object>NearestPoint and then dragging from its Geometry input makes an InputGeometry node, so no need to drag from the Input depot category.
*In the latest builds of Krakatoa since around Beta v2.1.8, you also get an ActiveType tool which could be the fastest way to find what you need when you don’t know where it is. You press the ~ key, or Ctrl+Spacebar, and type in the pink field to search. The search is performed on all Names in all Depot Categories including BLOPs, as well as the Category names, and the node descriptions. So you can find very obscure references. On top of that, some often used values like colors, direction vectors and so on are pre-defined, so you can type in “pink” or “right” or “pi” etc. You can even run basic MAXScript expressions, for example typing in “pi^2” produces an InputValue of 9.869605…
*Finally about the regular single-key shortcuts. There are a few rules I tried to maintain (not always successfully), and you can probably simply use the ones you remember.
-Obviously, *,/,- and + on the Numpad do mathematical operations. Add to that key 6 which has the ^ character on it that does Power.
-Then you have the input channels. They are generally created by holding down SHIFT and pressing the letter of the channel. SHIFT+P = Position, SHIFT+V = Velocity, SHIFT+N = Normal, SHIFT+C = Color, SHIFT+A = Age, SHIFT+L = LifeSpan etc.
-Holding SHIFT while pressing keys 0 to 7 on the top row of the keyboard creates basic colors.
-Holding CTRL while pressing keys 0 to 9 creates Float input values.
-Pressing keys 1 to 4 and 0 without any modifier key creates Integers. 5 does % (Modulo), 6 does Power, so they are exceptions.
-Pressing the period key (dot) at the bottom row creates a VectorDot operator. So I made VectorCross to be , because it is next to it.
-Using the same keys, pressing SHIFT+> and SHIFT+< makes Greater and Less logical operators, obviously.
-Pressing the /? key next to them makes a Logic>Switch, holding SHIFT while pressing the same button makes a Mux (because ? looks like an IF, so I felt it might be easy to remember)
-The = key makes, unsurprisingly, Logic>Equal.
-The - key makes Negate.
-The [ and ] keys make Sin and Cos, with SHIFT they do ASin and ACos, \ (to the right on US keyboards) makes Tan, with SHIFT makes ATan.
Once you understand the basic logic why these keys were used, it will become a second nature. Also, you can always create a node that is close to what you need, then change its settings. E.g. if you need a Float with a value of 10.0, you can press Ctrl+1 and then add a 0 to its value. Or if you need a NotEqual, press = and then change the node type from Equal to NotEqual…
Hope this helps.