It takes time to adjust to playing the guitar while standing. With practice and time, it will become second nature. The mechanics of holding the guitar, strumming, making chords, seeing the fretboard are different from sitting down.
If you plan to play standing up, yes you do. A good-quality strap will keep the guitar stable while you play. Ensure your strap isn't too narrow. A wide strap with some padding is far more comfortable than a narrow one without padding. Consider buying a strap lock for your guitar, acoustic or electric. A strap lock will prevent the strap from departing from the guitar, often causing damage to the instrument.
A guitar's action refers to the height of the strings above the frets on the fretboard. A low action means the distance between the string and the fret in minimal. (A small gap) High action is the opposite of a low action where the distance between the string and the fret is great. (A larger gap). Experienced guitar players often make adjustments or even full setups themselves. Unless you are sure you know what your doing, seek out a professional to sort it out for you. When a guitar's action is correct it is easier to play, it makes playing [...]
If you are just starting out, then a little buzz is acceptable, in time as your technique improves, the buzz should disappear. Are you strumming really hard, does the buzzing diminish if you strum easier? It may be your strumming too hard in which case you need to play less aggressively or have the action of the guitar checked by a luthier. Raising the action a little might help. Back to basics; confirm your fretting hand is in the correct position and that the fingers are contacting the strings at the right angle and just behind the fret. Do not [...]
If you are a beginner, just starting out learning to play the guitar, your fingertips are likely to be soft. When you fret a single note or a chord, the string will sink into the flesh of your fingers. When this happens, another part of the finger may be contacting another string. As you develop calluses, this occurrence is much less likely as the calluses develop, the string will not sink into the flesh anywhere near as much. Another possibility is that the fingers are not appropriately angled as they contact the guitar strings. If they are leaning over rather [...]
It's not unusual to experience some form of discomfort when start playing the guitar as a beginner, especially your fingers. As you continue to play you will develop calluses on the fingers of your fretting hand which will lessen the discomfort considerably. If for any reason you stop playing regularly for a time, it's likely that you will lose those calluses. Don't be disheartened, your calluses will re-develop in no time. If you have any persisting pain, it would be advisable to have the setup of your guitar checked. Particularly the action of the guitar. (The height of the strings [...]