In response to your first question, when building a set for actual play, quantity is more important to me than EXACT quantity. If you ever sat down in a cash game, you know that chips will at times dissappear (especially in the lowest demominations), and my biggest concerns are twofold-

1> Do I have enough chips to service the game?
and
2> Are these chips unique enough that it is unlikely for players to run in counterfeits?

For example, in the photo below, notice that the pink 8g diamond clay (we use it as a $1 chip) is marked 'RatPack'. I have over 2,000 of that particular chip, and while some of my newer pinks are custom hotstamped, many of the older ones still in circulation (like the one featured in the photo) were lovingly hand stamped by my teenage daughter, and these also feature silver marker strikes on the edges. These chips were purchased for less than .10 each, but if you come to my home game or to any charity event where these chips are being used, it's unlikely that the riffraff will attempt the hassle of trying to run in counterfeits against them.

I hope this answer was useful.
Regards, Smokey