RENEW SITE

I am not a professional WordPress programmer and expert.
In order to understand I asked I must write.
I have a website tiulim.net and it is in the GEOPLACE VER 3.8 version which is very old and I also have problems editing. It is located on an expensive external server

For this I intend to install a new version of GEOPLACES 4.4 on the site and in the storage of WordPress with a temporary name (which will be changed at the end to the original – after transferring all the materials from the old site)
I will also do a different routing of articles with different categories. My upgrade to what it was
Since my articles have been published in thousands of places, as a result of the transition I may miss links in which I have invested thousands of hours.
In my mind that every post I move from the old site to the new, indicate on the new page, in a certain place the source link.
I have 4400 articles and thousands of pictures. I intend to do consolidation and cancellation of many articles. And in the search engines, page 404 will appear.
What do you do? Is there an explanation? A video?`

The page I need help with: [log in to see the link]