I'm no expert, but you'd have thought they could have at least moved all the issues that were in the Marvel promotion over to a separate (temporary / bigger) server.
That way, even if the promotional content got swamped and went down, at least the rest of their material stays accessible and those not taking part in the promotion don't notice any drop in service.
Apparently, even the DC digital store (which is just a front-end for the DC content available on Comixology) experienced some slow down because of all this.
Possible... I'm not sure who Comixology use for storage but you would've thought something like this had been planned for a bit longer than 5 mins
Yep, they should've definitely put something into play to cover increased demand.