Expansion Tank Questions - 2006 Saab 9-3 Sportcombi with 2.8 V6

Yep, more questions....I've been doing all the maintenance that doesn't require the Tech 2 over the last week or so. I have the 'low coolant' warning light despite the fact that it isn't low. Apparently this is a common problem with the expansion tank's guts getting cooked. I pulled the old one and the insides were all rattling around like a kid's toy box. I've replaced the expansion tank with a new one and the new small hoses, but I didn't replace the cap. I still got the 'low coolant' light. I checked it a few times and it appeared to be fine. The other day when I stopped the car there was a small puff of steam from the location. I panicked and popped the hood. There was no moisture to be seen. I figured it might have been a small amount of liquid that got jostled onto the turbo heat shield as I'd had a bunch of stuff apart the day before (trans oil fill, plugs, coils, expansion tank etc). Last night, clipping down the freeway I heard a pop, felt a light thud in my foot through the firewall and immediately started looking at gauges. I pulled over in a mile or so and had copious amounts of steam coming from under the hood. I waited for it to cool off and discovered that that pita hose at the bottom of the expansion tank was off. I don't see the wire clip so I probably didn't get it secured properly.
My questions are:
1) Does O'Reilly / Schucks /AutoZone stock these clips or is in an online only thing?
2) If it popped due to the system being over pressurized, could that mean that the cap isn't doing it's job? If so, is that cap available at

O'Reilly / Schucks /AutoZone stock these clips or is in an online only thing?
3) Any other ideas what the problem could be?
Thanks for any guidance.

Miracle of miracles, the clip is still there. No idea why the hose popped off. I appear to have lost about 3/4 of a gallon of coolant (if I don't have air in the system). Any input/ideas on the cap? It looks fine but maybe I should just get a new one anyway.

Did you reuse the original clip? and new cap with the new tank is always a good idea.

Yerah, I re-used the original clip. There wasn't a new one included with the kit. I'm ordering a new cap tonight. I had some steam as I was driving and when I pulled over I couldn't pinpoint where it was coming from. It may have been from the overflow tube by the cap. I'll check the level again in the morning when it's cold.

May have loosened the lower hose, somewhere below, in my zeal to get it reconnected. Low coolant light isn't coming on anymore, though I suspect the fluid is low. It's been piddling a bit after driving but still can't pinpoint the leak. Hopefully this weekend...