It is fine, pour your beer in a glass, stop when the yeast gets to the neck. As for the question of everyone having yeast in their bottles, it depends on the brew, some of mine do, some dont.
Yeah that's normal. If you have a slow focculating yeast strain and bottle in a week or so you'll get even more. I've found by leaving my beer in primary for longer, like 3 to 4 weeks, more yeast will settle out and you get less in the bottle.
Nope, 100% normal. In fact, it'd be weird if it wasn't there. Some folks pour it right in their glass, others leave it behind, totally up to you. It doesn't affect flavor much, but makes the beer cloudier than it would be otherwise. In something like a stout, you won't notice anyhow. In a lighter beer, you may.
Basically,the longer it spends settling out in primary,the less yeast trub you'll get in the bottom of the bottles as they carb.condition & settle. I've gotten no more than a light dusting on the bottom to maybe 1/16". Can't avoid it,as the yeast settles out after eating the priming solution.
Ya I have a decent amount after 3 days on the bottom of my hefe from fermenting 18 days. No big deal for me, I will just warn the others that want some. I'll be expecting they'll freak a bit, lol.