If you like the length of this dress, what other dresses have you found?

Most of the 'Dresstells' dresses are a nice length.

How do you choose the size?

One of the images for this item is a measurement chart, also available through the link that says "size guide" or something similar (hidden near the bottom of the description). Measure your bust and waist, then choose the size that best matches your dimensions. Be prepared for your size on their chart to be two or three sizes larger than your normal - I normally wear 8/M on top and 10-12/L on bottom, but their scale has me as XXL The fit is a little loose but not loose enough for me to go down a size without risking it being too tight at either my waist or bust, maybe both.

Does the material for this dress stretches?

Yes, a bit. The bodice and skirt is a nice, thicker material with some give. Though I found the sleeve opening to be a bit tight and non-forgiving. It dug into the front of my arms anytime I reached out and I have slender arms. I ended up returning it, unfortunately. It looked pretty though!