1- Haven't tryed the yeast but have tried others
2- Temp extremes didn't help but one way to find out. Make a starter and see if fermentation starts. If it does, it is okay I would say. If it does not, find a local homebrew store or just order another. One way to really tell is make a small batch for a growler and see if the beer turns out okay (just take a small sample after primary and see if there are any bad off flavors). It nothing is wrong, just bottle the yeast in a sanitized empty water bottle and pitch into a new batch you brew.
3- The ones I have bought are like that and have had no probs. Just shake it, wait 30 min and pitch into wort.
Like I said if your really worried, take a full batch of wort and take out a 1/2 gal. or full gal and ferment it on the side. You can always reuse the yeast for another batch. Plus reusing save $$. Hope this helped.