Tell us about yourself!
Sorry, don't know any websites that sell these items. The gauge valves are sold at supermarkets! (along with non-gauge valves); I found the screw-down clamp at a local"micro tech" store that sells tools.
I don't know about other Asian countries, but in Indonesia, one can purchase the connecting valve with a gauge on it that shows "Full" to "EMPTY" and graded steps in between. (about USD 5/-)As to leaks, here one can also purchase for less than USD 2/- a "tie-down" that engages the valve to the tank with a tightening handle. Hard to get a leak when the valve is completely tied down!
The damage that ironing might have on a fabric is where there is a crease - I would suspect that items that are ironed with ironed creases might have crushed and broken fibers.