The best way to avoid an informal elite is to get everyone stuck in and knowing what is going on. If that does happen you can be fairly sure that there is something wrong, politically, with such an organisation. We are quite happy to work with other anarchist groups as long as there is a basic level of agreement. Factions would have to support the majority position but would have full access to the internal bulletin and the organisation's journals to argue their ideas. No other political groups organise in this way.
Any parliamentary party is run on a hierarchical structure.
The higher you are the more control you have. Real decisions are made by the elected TD's over the heads of the members and the most important decision are made by the leader of the party and a couple of cronies. We are told to have faith in people who we are told know better than us. A similar method of organisation is used by Leninist organisations. Leninists do not believe that the working class can develop political ideas.