Though I think it's a slightly under-qualified question, I can make some assumptions and try to give you an answer to the first question.
Your Sony is a relatively 'weak' 80-watt receiver (certainly blown away by various 55-watt HKs in the power department) but Axiom speakers are very efficient, and the towers moreso than the bookshelves.
You won't clip at reasonable, or even loud volume levels. I'd imagine you would clip at extreme volume levels. More power certainly couldn't hurt, but I'm pretty confident your concern won't be a problem.
