Originally Posted by
Aznman
1. Which brands make the best mechanical brifters that are able to interconnect with each other?
Brifters don't interconnect with each other. A brifter's shifting mechanism connects to a derailleur, and its braking mechanism connects to -- you guessed it -- your brake caliper.
As for brands, Shimano, SRAM, and Campagnolo all make good brifters. Microshift is another company that makes brifters, often an lower price points. I haven't had my hands on any of their products, but feedback seems to be generally positive.
For any given model of brifter, you need to be aware of what brand/model(s) derailleur they'll interface with and how many cogs ("speeds") they'll work with. You can't just cobble together random combinations of parts like a 10-speed SRAM shifter with a Campagnolo derailleur and an 11-speed Shimano derailleur, for example. Sorta like you can't just throw an alternator from any Nissan into a Toyota. You need to cross-reference what'll fit and what'll work.
Originally Posted by
Aznman
2. How do these mechanical brifters work anyways?
Generally speaking, they're just an indexed shifter and a brake lever in the same housing. Click the shift mechanism one way and it'll pull just enough cable to and you upshift a gear. Click the other way and it'll release just enough cable to downshift a gear.
Originally Posted by
Aznman
Are these types of brifters easier to malfunction?
They're intricate little devices, with a number of pawls and springs. With such a complex mechanism in a tiny little housing, occasionally something will go wrong. "Occasionally" is pretty darn rare, though. They're reliable devices.
If you search these forums, you'll probably find that the most common malfunction is dried up lubrication. Flush with solvent, re-lube, and you're back in business. Another common issue is cable fraying/breakage. It can be a pain to remove a cable once it's damaged, but once it's out, just replace it and you're back on the road.
<EDIT> Oh, and as for "different hand positions" as mentioned in the thread title... All of the major brands make their brifters such that you can brake and shift from multiple hand positions. With the exception of some older lower-end Shimano brifters, you can reach the brake lever and shift paddles/levers/buttons from the hoods or drops.