A charm pack is a pack of Factory cut 5" squares usually of the line of one fabric, Moda puts out a lot of charm packs in their fabric lines. A jelly roll is the same type thing as a charm pack but in 2.5" strips. A lot of times, again, it will be a group of fabrics in the same line, or sometimes it could be a group of bali fabrics or one that a quilt shop put together. They are ready cut in those sizes and yes, there are lots of patterns out using those cuts of fabrics. Though, they are not pre-washed and if you are a prewasher, these may not work very well cause they can fray and shrink up smaller than what you want them to work with. Personally, I don't usually pre-wash cause I like the look from a little shrinking with the all cotton Batting I use.
As far as Block of the Month, you can make it into a quilt when you have completed all of the blocks or you can make pillows or if you find a block or two you really like you can then combine those into a quilt. It is a good way to learn how to make a lot of different blocks.
Don't worry about questions, we are were there at one time or another. I am still learning a lot of things about quilting and there are a lot of knowledgeable people here.