It's all speculation, so it's somewhat luck of the draw.
But a lot of the coins suggested here have already been pumped, so it's unlikely they will do a 100x.
No one can really predict it, so to find the gems, you really need to do some research. For that I'd recommend checking out some low cap coins that haven't been pumped, read the whitepaper, announcement, join their chat and get a sense of how the community is. If that looks good, checkout the chart and look to see if there's potential.
Correct. Those coins needs a huge community to hype it because they are really good at shilling when they are great in numbers. They exist in every social media like twitter and also trollbox and there you have the recipe for very possible 100x.