You will mostly need to know your girth so what is that? Go with flared. No they are very solid, the elliptic is like glass but the flared are a hard plastic. If you are 8 inches already I would go with 10 or 11 that way you have room to grow. If you do however want the 9 inch cylinders I can give you a deep discount on some really clean used ones here:
well I would go for a focus, length or girth i.e. if your focus is girth then get a tube .5 inch longer than your BPEL and 1 - 2 inches more girth, if you want length vice versa. Also get a heating pad and heat up you tube before sessions and during. I am having great results with 3 x 20 mins sets with edging between, every other day