Hi Kay'lon,
-- Reducing beating at sample loop point:
Many samplers have a function called "smooth", "crossfade" or similar. This usually takes away the beating. Sometimes you need to set loop points manually in order to listen and find two parts of the sample that sound similar in timbre so you can place the Start Point and the Loop Point there.
Sampling longer snippets can also help. But in some rare cases the opposite might be true; for example regarding plain wave forms where there is no modulation happening in the sample. In that case I personally think sampling just one or a few amplitudes of the wave form gives the best options for treating a patch with the sampler's modulation arsenal.
-- Best way to sample synth sounds:
This is all up to two factors: the accuracy you are aiming at and the nature of the source sound to be sampled. For the highest accuracy you should sample every half note. This will need a lot of disc space though and also large RAM on your computer for the sampler to read in a program/patch. One can listen to the synth and make decisions on maybe only sample every third half note at parts of the range where notes do not differ much. Myself I had good results with sampling every third half note for the simple reason that I am not only a syntheist but also a samplist and as a samplist you tend to like the way a sampler subtly changes the sound of a sampled synth. This especially comes through in pad sounds where there is some kind of cyclic modulation happening in the synth's source sound; when a sampled note is played back in the sampler at a different pitch such cyclic modulations will happen at a different speed and collide with the modulations of other notes in a chord, resulting in a fatter sound and more busy dynamic texture.
Again, it can turn out useful if you keep in mind the possibility of turning off the synth's modulation and just sample the raw wave form in order to apply the future sampler's modulation to that.
Some synth sounds rely totally on modulation, maybe an onboard filter, as a "synth efffect" and in such a case you may want to just sample, two or three "takes" of that particular effect. A full keyboard range sample program would be way over the top here.
I sampled all my analog synths before selling them and used a specific application to carry out that task during a period of several hours/days. THe app was called AutoSampler but I'm not sure it still is available because Apple bought the company (and hopefully that awesome workflow will become part of Logic in the future?). Sampling a huge library manual sucks big time. There can't be enough rainy days on the planet for justifying such a boring activity.
