To a mechanic, just about any kind of repair using older bike technology is quite simple and much of that is easily learned by trial and error. The exception being wheel building and wheel truing, I have met many good mechanics that can't quite figure that out.
Sheldon Brown website has excellent basic articles on many bicycle topics. Sheldon is no longer alive, but others appear to be updating his website, but his site is often a few years behind when it comes to newer stuff.
Sheldon Brown-Bicycle Technical Information
A 5 foot rider might have toe overlap issues on just about every bike she rides. And the bike weight as a percentage of her body weight will likely be higher, meaning less ability to carry a load of weight. But otherwise, pretty much the same as anyone else.