"Has any one worked with bamboo? Is it like a light weight cotten, better for summer items?
I am currently knitting my first sock using Regia Bamboo sock yarn. It's 45% bamboo. I'm a newbie and certainly no expert, so I will just tell you what it says on the label which is that bamboo makes the material light & "breathable" (sorry, I'm translating this from german). I assume they mean that it's good for potentially sweaty feet (ewwwww).
"When you buy yarn how do you know how many projects are in a skeen?"
I have found that most online shops list how much yarn you need for sweater sizes, etc. More importantly, most patterns will tell you how much you need. And I think it's a matter of experience too. I bet some of the experienced knitters will tell you that they can calculate how much they'll need through experience.
"Why are some sold by weight, and others by the yard
I have no idea!
"Do any of you ever buy more yarn for a prodject than what the pattern calls for...just incase?
I know trust the pattern...I do...it's me I am having issues with
For the few projects I have knitted so far I have bought the recommended amount of yarn + one skein. This kept me from being worried throughout the project that I was going to run out of yarn. But that's just me.
The first thing I knitted was a scarf. I went to my LYS and had the saleslady help me pick out the yarn. The amount she recommended and sold to me would have knit a scarf to fit around my house. So I have a nice, long scarf, a hat out of the same yarn and one and a half skeins left over. I'll probably make myself some mittens with them one of these days.....