Well some of those questions fall outside of what you're really going to be directly doing with XtraDB. I'll answer the questions that would be more directly related to the story though.

For backups we use another Percona tool: http://www.percona.com/software/percona-xtrabackup It's free and works great.

Disaster recovery is standard stuff. Backups/hot backups to external and recover as necessary (generally we try to keep that to never).

Monitoring is outside of the scope of XtraDB, but take a look at MONYog.

Now clustering is more XtraDB related. The clustering is nearly dead simple. If you use the (technically deprecated) wsrep_urls configuration option you can spin up a cluster from scratch without needing to worry about master location. Not sure WHY they deprecated this, I guess some people had issues with it, but it has worked fine since the beginning for us.

You don't need a master/slave relationship unless your writes are really sky-high, or same with reads. Basically make sure you have a good number of wsrep_slave_threads defined (double CPU cores seems to work well for starters).

Sharding, partitioning and archiving are kind of outside the direct scope of XtraDB. You'd be better served looking up documentation online for more info than I'd be able to provide in a short post here. Insofar as it ties in to XtraDB though, I think there's nothing wrong with jumping straight from a single DB node to this solution. You just really have to have the additional CPU/memory resources to add more nodes (you need at least three to keep the cluster alive if one dies... two will get you split brain if one dies). I believe e-mail is in profile if you have more questions, but this should cover the big stuff.