When crocheting in the round I usually place a marker than crochet in a spiral.. instead of joining then doing a ch-1 then on to the next row just crochet into the next spot and you will be crocheting in a spiral. You will not need to join/chain/start a new round as you will be working continuously in crochet stitches and avoiding the joining that causes the bump. You use the marker to know where your round starts in case you need inc. and dec. It might be hard to understand until you try it.
I'm planning to use seam binding (bias) tape for the first time (the kind with a double fold) and have a question about it. The tape I am using is cotton, and I will be using it to hem a circle skirt which will be machine washed and dried. So... will the tape shrink noticeably or will it be ok since it is cut on the bias. The skirt fabric is some sort of unknown synthetic- thrifted fabric. Thanks!