Assist with Update of Joomla Site

Need to update to latest Joomla, however having some issues after PHP updated, and further issues after Joomla updated. I need some one who can sort this out on a staging server for me before pushing to live. Need to isolate which files, template entries etc are changed. This is a one-off, but there is more development and upgrading work to follow over the next few months as we sort out some CSS and design issues, and then undertake some custom development to better integrate a fairly useful set of extensions, if I can find a good resource I am comfortable with. A rough road map of the longer term tasks I need to address are: 1. Get the upgrade to Joomla 3.9.3 / PHP 7.3 working well 2. Address some issues around the template and the framework it runs on. This may be to replace the template and use a new Bootstrap template, or just custom develop one that does what I need. 3. Some custom development, including SQL and administrative forms to better integrate / replace extensions which are pretty good, but not quite right in some spots. 4. Get Moodle installed and up and running correctly, dealing with some issues in the hosting in a sub-domain. 5. Address SEO / web marketing. - may go to someone who specialises in that. This project is for part 1 above only. But I would like to find someone who having completed item 1, can then engage with me on projects for the remaining items, in a cost effective, well managed manner. It may be that we seek someone who will only do the technical side - items 1 to 4, and another provider will manage item 5. I need to be informed of all the files and changes made, so we can manage impacts on future upgrades to Joomla and extensions. There is a reasonable budget available to cater all the above items over the next two to three months or so.