Well you are trying too much with wordpress. No doubt wordpress is a good platform but I am really not sure how it would perform given the multiple items that you plan to run on wordpress.
ecommerce / job / classifieds ad. I think you need to ask someone who has done such a large scale integration of multiple things on wordpress. Basically here is how wordpress word work and how you could set it up if you really wish to set it up.
- For ecommerce you have already selected woo commerce so no suggestions except you can also check out others like wpecommerce and others. Like I believe woocommerce main plugin is free but if you need additional features you need to buy separate plugins so you need to evaluate the cost.
- For Job & Classifieds you have 2 options with you - one is either buy a readymade theme / plugin that supports this or you need to build a custom post type for job and classifieds and then add custom taxonomies and custom fields to each of the listing and then build the site yourself. For ready made themes I am not sure if there is a single theme that supports both jobs and classifieds so either you might need to create subdomains like jobs. your domain . com and classifieds.yourdomain.com and then create separate installations for each - ofcourse you would be able to share the user tables but overall it would be a separate install.
- Given what you are looking at you want free themes etc which I doubt you will get but you could slowly build upon a site using wordpress if you know coding. As discussed earlier you can easily create a theme in wordpress and you will then need to use custom post types / taxonomies and custom fields.
Limited options for filtering data are available to please evaluate everything.
I think you should also evaluate Joomla as an option like for joomla you have virtuemart for ecommerce and many extensions for jobs and classifieds so you can check the joomla extension directory.
I am no authority on such integrations and the above are simply my personal views and I might be 100% wrong in my views so its best you wait for other responses and you yourself take another view and then we can finally decide which is best in the above scenario once you have more views from others