Booster works as a reverse proxy, so for each incoming request a connection is created to the backend http server (eg Domino). These are http connections so are by nature stateless, therefore cannot be pooled. If the backend server supports Connection: Keep-Alive, then the connection is not broken and multiple http requests from the same client are proxied over the one ip connection. One user may create multiple simultaneous booster connections, depending on how the browser decides to send the data.
How Booster works with Domino is determined by a variety of factors in both the web browser's http headers and the server's http headers on reply. eg whether the client supports gzip compression, whether the server has already compressed the content, the content type, what rules for caching have been set on booster, etc. This is difficult to answer in a generic fashion.
Session timeout only applies to Tornado server. It controls the amount of time a session will remain idle on the server before being removed. boosterporttimeout controls the amount of time booster has no data from the client or server before severing the ip connection. This figure may require a little tweakign depending on what your http server is doing, for example if the is a lot of http server processing before a reply is sent, then a longer timeout value will be required. We recommend using the default and then tuning booster.