[SalesForce] SOQL query all tasks and events with opportunities and any connected campaigns

The short answer is not easily, or at least not with a single query like you're showing above. If the WhatId is not associated directly with the account, you would need to query all related objects to the account, then the associated tasks. If this is in a trigger, making it bulk safe is going to involve a couple of maps.

This is one way:

select Id, Subject
from Task
where WhatId in (select Id from Opportunity where AccountId = :accountId)
and Type = 'Call'
order by Subject

The Relationship Queries documentation is well worth reading.

PS

On the subject of where to get the Account ID, probably the simplest way in a controller extension is this, though in the "new" case there won't be an ID hence the alternate logic:

public with sharing class MyController {
    private Id accountId;
    public MyController(ApexPages.StandardController sc) {
        accountId = sc.getId();
    }
    ...
    public Task[] getTasks() {
        if (accountId != null) {
            return [
                    select Id, Subject
                    from Task
                    where WhatId in (select Id from Opportunity where AccountId = :accountId)
                    and Type = 'Call'
                    order by Subject
                    ];
        } else {
            return new Task[] {};
        }
    }
}