stick to your normal size 28x30
tepphars have elasthan that make the jeans stretch out and if you can wear a 8X2 which denim is very stiff in 28 you wont have any dificulties to wear the tepphar with the same waist size.
Yes and you will be surprised by jeans details particularly the range of stitches below the crotch along the inseam. Great pair. Denim is thick and a it will stretch out (although it is made of cotton only).
Yes you are right color is similar (grey faded denim) but as long as i can remember the QP had no whiskerings and material is completely different ; 8QP is made with stiff denim when the JJ is soft, stretchy, and so comfy...