You will need velcro strap as the bike loosens up over time and will start falling apart from fold when carrying if not used.The other one with dahon on it is for pant leg so your pants dont get caught in chain,kinda nice actually.
As far as support goes there is some,but i found Dahon support to be aggressively arguementive to put it nicely.Actually sold my new Dahon at a loss after my Brompton arrived mostly because of that.To be fair others have not found that to be the case,guess we all see things different.