Django social networking site with heroku
apache Solr for fast indexing,
virtual-env ,
a library that provides connection pooling (SQLAlchemy),
django-evolution or south for migration.
Iam in a plan to develop a social networking site in *python/django.*I have decided to use following technologies to implement this.I have some doubt regarding these technologies which i had planned to use. If anyone can help me regarding this it will be helpful.I want to avoid the  bottle necks when it is scale into the thousands of connections .

Apache  as web-server
Mailgun cloud-based email service (Heroku addon)
RabbitMQ as a message queue(Heroku addon)if required
MySQL  5.1 as database system.(Xeround addon)
Git as file content management
Memcache to reduce database load (optional)
Heroku as a cloud based plattform(staging and live)

Which storage i have to use for static files delivery or any heroku addon is there for static or content delivery?
Please advice.
Thanking you in advance