Is there a basic, universal recipe for cupcakes?
From personal experiences, reading cookbooks, and making far too many baked goods I've learned that it can be tricky to just adding extra ingredients while maintaining a universal base cake or cupcake recipe. However, with good judgment and some basic ingredients ratios you could come close to an archetype.

Some ratios (by weight) of basic ingredients include:


Pound Cake - 1 part each flour, eggs, fat, and sugar
Butter Cake - 2 parts each flour, and sugar. 1 part each eggs and fat


Beyond that here are some basic rules


The ratio of sugar to flour should be 1 to 1 in most recipes, maybe slightly higher in the sugar side of things. 
Same with eggs, they should weigh about the same as your fats, possibly slightly more.
In general liquids measurements (including eggs) should weigh the same as or more than the sugar.
Eggs are in interesting ingredient. Whites tend to dry things out while yolks tend to make a richer more velvety texture. More yolks to whites (like in a yellow cake) make for creamer textures, the inverse make for drier more crumbly textures.
Then comes leavening. A teaspoon of baking powder per cup of flour often does the trick. 


Adding extra ingredients however can throw off your recipe. Bananas for example can replace some of the sugars and some of the fats. Peanut-butter some of the flours and some of the fat. Adding enough chocolate chips, though they stay pretty much contained, may not interfere with the other ingredients but will increase the density of your recipe and may require additional cooking time. Adding coco powder instead of flour usually deems the need for more egg yolks and sugars. 

Really you just have to play around until you get a good feel for things.