What to use to build this site?

Hi all, I would like to create a site that works on the concept outlined below.
I love using WordPress so started looking for plugins to fit the bill.

Could anyone suggest a combination of settings/plugins to achieve this, or point me in the right direction of something I can use that can handle this behaviour.

Concept:
– PersonA can create an personal account.
– Website collects personal info fields for PersonA
– Website also allows PersonA to fill in with Custom Fields X,Y,Z
– PersonB also creates a personal account and can search for Custom Field X and view the details of Custom Fields X, Y and Z (but no personal details of PersonA)
– PersonB can then send PersonA an (anonymous both ways) private message.
— Better still, can choose from a selection of pre-loaded messages to send (no free text)
– PersonA receives an email/notification of their new alert/message.

Option 2 – As above, but with a extended:
– Each user account could have multiple sets of Custom Fields X, Y and Z
— That is, they login with their “persona account” and through the one account, can receive alerts/messages reported through any of their ‘listings’ – ItemA(X,Y,Z) ItemB(X,Y,Z)

Appreciative of any help I can get to find the tools to build this site.
Thanks in advance!