First of ask you why you're asking these questions - we'd all be able to give better answers that way.
I think you need to go to a store like JoAnn's or Hobby Lobby and take a look at their fabrics and touch them and learn their names.
If you did that, you'd already have an idea that the typical cotton twill is a durable bottomweight fabric. It could certainly be made lighter - so weave and fibre aren't absolutely everything. Weight and how the fibres are spun is also important - this is why people go to fabric stores to touch the fabric in person or they will order swatches if buying online.
If it will fade quickly depends more on the dye than the fabric. If you're buying commercially dyed fabric, it's not something you really need to worry about - and if dying it yourself pick a quality dye that is suitable for the fibre and follow the directions. The only time I'd worry about fading is on something with an unusual process or finish.
If you went to the fabric store you'd also know that it's not going to "come apart" easily. I really encourage you to learn more about fibres and weaves and do some research on your own. There are pages and books that go over this basic information.