Yes, you are technically correct on both. However, I'd say "I am waiting for an opportunity to meet her." It better conveys the sense of ongoing action in the present.

As for the second question, I'd rather say: "I had been always waiting for the moment/to get the opportunity to meet him/her...." "until it finally happened". Whereas, if you say "...was always waiting..." you'd probably have a "but" afterwards. The above mentioned tense denotes an action that was interrupted or an action/situation that kept being repeated but was never finished. So, it all depends on the facts or on what you want to say.