Sort of. With the piano, one can play as many notes as they want, but the placement of strings on a guitar makes it sometimes impossible to play the chord with the the notes appearing in the same...
No.
A Cadd9 is just what it sounds like: a C chord (C-E-G) with a 9 (D) added. Thus, it is C-E-G-D. You will *not* want to play it as C-D-E-G because it will sound like mud.
A Csus2 is a...
I can't tell if you're asking this question from the perspective of a piano player or a guitar player. Neither of the instruments you've mentioned are pitch-class transposing instruments. So the...
If you're struggling, a method I use which helps is: Take some paper. Write down the notes of the chord (C major for example would be C, E, G) Find these notes on the piano Voila!