Nope, the Spirit Companion can be reconjured immediately, there is no wait time required. The penalty for having it destroyed is the hit point loss to the shaman. As long as the character can withstand the damage you can keep bringing the SC back again as often as you want.
SCs are conjurations, and as such are not affected by ANYTHING. The specific rules for Spirit Companions do allow melee and ranged attacks (but not area or close attacks) to do damage to the SC, but no other effects or conditions will apply and since they don't have actual hit points an attack is relatively harmless to them unless it does enough damage to dispel the SC.
There are admittedly a few minor areas where the rules are hard to interpret on the subject, but PHB2 p219-220 (conjurations), PHB2 p119 (shaman class features), and PHB2 p120 (Call Spirit Companion power) do cover everything.
The main thing to remember is that a conjuration is not a creature. It is a magical effect. Unless a specific rule says otherwise it is not considered a creature (and thus is not an enemy or an ally) and doesn't follow any of the rules for creatures etc.
I don't know of any errata for the Shaman class or for conjurations (beyond the rehash in PHB2). The 4e FAQ I believe has something to say about conjurations and may have a clarification on spirit companions as well, you can check there but IIRC all it talks about is that conjurations can move horizontally without needing to have anything under them for support (like over a pit), but cannot move vertically at all. How exactly to interpret THAT is up to the DM (IE can it go up a set of stairs).