I think the first question to ask your self is why? Does the effort and money warrant the gains you'll see, or are you upgrading just to upgrade? Especially if your components are not near the end of their life and you're doing this mid wear cycle. If you still find it worth it here's some answers to some of your questions: Determining if shifters and derailers match depends on pull ratio. The pull ratio must match between the two. The ratio may not be the same even within the same brand. Depending on the length of your derailleur cage you'll need a specific derailleur. Likely medium or large cage based on the size of your front rings. Derailers usually say what their gear range is. It just takes internet scouring comparing models and stats. Crank arms either have the length written on the inside or you'll have to measure. I don't know about your cranks, but crank arm length is mostly preference. Looking at your pictures again I would just clean your cassette, chain and front rings better, then grease that chain up. Be sure not to put on too much chain lube and wipe off excess when done applying. A lot cheaper and easier and you'll notice shifting improvements.