How can I make a WordPress database portable and url independent?

Issue

I am about to embark on some WordPress development in a multi person team environment. (3 or more people working on the same codebase at a time, each developing locally)

With other CMSes we have worked with, everyone has pointed their installs at the same database and because of how that CMS/database has worked, it has meant we can all have the same content feeding into our installs (located at differing urls) from the same database without much issue (other than occasionally having to sync uploads folders)

My question is, with WordPress, what prevents us from using this same approach and how can we solve these issues?

eg. Three copies of WordPress all running off of the same database.

http://dev.local/developer-a/
http://dev.local/developer-b/
http://dev.local/developer-c/

etc

I hope it goes without saying that this will only be in a development environment prior to launch.

Main issues

1. References to specific urls within the database (wp_posts and wp_options tables it seems)
2. If one person installs a plugin, the other installs won’t have it and will cause concurrency issues in the database
3. Keeping uploads folders in sync

Current Solution

Currently I have the beginnings of a solution for the first issue in place. I place the following in a file in my mu-plugins folder.

The code essentially filters the post content as it goes into and out of the database by replacing any instance of the url with a unique token.

<?php

define('PORTABILITY_TOKEN', '{_portable_}');

function portability_remove_home($content)
{
    $content = str_replace(get_option('home'), PORTABILITY_TOKEN, $content);

    return $content;
}

add_filter('content_save_pre', 'portability_remove_home');

function portability_add_home($content)
{
    $content = str_replace(PORTABILITY_TOKEN, get_option('home'), $content);

    return $content;
}

add_filter('the_content', 'portability_add_home');
add_filter('the_editor_content', 'portability_add_home');

I have set the home and siteurl options via php using the environment of where WordPress is installed to work them out. (again, this is for development only) This means that to each individual install WordPresses post content will look like it is running on that url by the time it gets to the client.

<?php
if (!defined('WP_HOME'))
{
    // define WP_HOME (aka url of install) based on environment.
    // IF THIS ISN'T WORKING, DEFINE IT EARLIER.
    define('WP_HOME', 'http://' . $_SERVER['HTTP_HOST'] . str_replace($_SERVER['DOCUMENT_ROOT'], '', dirname(__FILE__) ) );
}

if (!defined('WP_SITEURL'))
{
    // Assumes WordPress is in a separate directory called 'wp', relative to WP_HOME.
    // IF IT'S DIFFERENT, DEFINE IT EARLIER.
    define('WP_SITEURL', WP_HOME . '/wp');
}

The second and third issues seem solvable with the appropriate symlinks (all developing on the same machine)

Actual Questions

1. Can I improve my handling of the differing urls in anyway? Is there anything I have missed that will have the url hardcoded into the database?

2. Any gotchas I should be aware of with the symlinking?

3. Any other issues anyone can think of?

I realise these questions are very specific, if anything is unclear, comment on this and I will amend / clarify.

Thanks.