Hi there, I'm Matt Sergei (do call me Matt, please) and would like to help rewamping your site.
I don't know who you want to compete with and if you intend to have job seeker profiles yet this is in my visionary proposal:
1. WordPress website can stay the main architecture. It offers several plugins (see below for more) yet the site would need to be optimized for speed and mobile devices.
2. Structure all jobs to categories and tags (similar to what you have now) to follow WordPress/Google recommendations. So several categories (unique, e.g. job types) and categories can have several tags (shared, possibly also intersecting in several categories).
3. Then a search would be vastly improved and prominent on the first page. It should offer searching by tags (most frequently searched on front page, relevant for a category a job seeker searches currently etc). With pressing a tag button displayed e.g. less typing. There's a plugin to be used as a base for that.
4. Banners - only needed (for your earnings, too). On front page and on top of search, search results, category and city/area browsing. You can imagine different advertisers/employers interested in.
5. Offer user profile creation, saving preferences and once a day e-mailing matches (if any). Allow adding a CV, an image and a video (only from YouTube, Vimeo etc).
And more. That's how I would enhance all - job seekers first.
Otherwise I'm a webmaster for 26 years and WordPress developer for 11 years.
Regards,
Matt