specs would be good, as mentioned previously- edit -seen specs, should be ok, but don't expect every option on full, you will have to make a compromise or 3
offline campaigns/missions- see herehttp://airwarfare.com/sow/index.php?option=com_jdownloads&view=viewcategories&Itemid=73
user made ones imho are better than the 'somewhat limited' (trying to be polite here) campaigns that come with game.
regarding AI- the quick missions do a bad job here, but it is quite possible to 'tame' the worst excesseshttp://simhq.com/forum/ubbthreads.php/ubb/newreply/Number/3557054.html
there is meant to be some improvement in comms in forthcoming patch (and about time too!)
Steam- afraid it's compulsory- but if your interests are offline it is quite easy to switch steam to 'offline mode'- at least this way if your internet goes down you can still play