Wordpress Development Support

I'm English and run a small web agency based in Spain.
I need to work with someone to build a long term working relationship but to start need ad hoc, hourly, freelance or "per task" work until I have enough volume to be able hire someone either part or full time.
We work primarily with wordpress & use theme builders like DIVI & Elementor for the majority of our basic sites. We often get asked for modifcations, extra coding, adding api's & xml feeds etc that I need someone to help with.
The role would also entail problem solving on existing sites. For example I currently have a wp-admin "white screen of death" 500 error that I cannot fix. So it would be a mixture of support for existing sites, quoting for work on new client projects & creating our own in house developments when required.
The right applicant would need to know html, php, sql, css frameworks like bootstrap, java (perhaps) and be very competent with wordpress & the server side applications to problem solve wordpress.
Moving forward I have ideas to develop themes and plugins both for existing themes & clients and then for sale on marketplaces like themeforest.
We'd use management tools like asana for projects & time tracking. The time difference is not as important as reliability. if I create a task it would need to be looked at as quickly as possible, quoted for, scheduled and then completed on time, or as near to on time as is realistic. Being updated on progress is important so I can feed this back to clients.
Trust is a very big part of my expectations, we would work together and hopefully, in time, move forward into full time employment where you would become the technical backup to our marketing efforts here.
I look forward to hearing from you.