How does initial tor connectivity work?

[Scott Ehrlich]

I'm steadily learning about torproject and privoxy, learning that tor
is the conduit that actually aides with anonymizing the user.   I saw
the comic/graphic on tor's page showing how the initial connection is
made to a server.

I'd like to know are the full details on how said server connections
are made.   Does the client reach out to the same server every time?
If an entity/person wants to perform multiple searches, all
anonymously, hoping, or so long as nobody is sniffing traffic between
the entity/person and the server destination, will tor reach out to
different servers at various increments of time to learn new servers,
essentially utilizing spread-spectrum techniques, but a potential
passive sniffer keeping track of the servers being hopped to?

Is there anything to truly prevent the same machine or IP from being
sniffed while connecting to a tor server to enable traceback to the
originating entity/person, provided there is no in-house rogue user or
system - that the rogueness is external??

Thanks.