Sorry if already answered someplace....
I have a PS4 Pro now with a few games in progress (Crash 4, Ghosts of Tsushima, and Crosscode). Will i be able to (if i dont finish them all first) download those games to my PS5, and will my PS4 save i have now work on the PS5 and allow me to continue, or is compatibility with PS4 titles only based on if you start a new save on the PS5?
Yes, you will be able to download and play these games on PS5 for free if you had them digitally on PS4. If you had them on disc you'll need to put the disc on the PS5 to play them, so make sure you buy the PS5 with disc drive.
Regarding the savedata, you can move it from your PS4 to your PS5 via USB external storage (like a pendrive or USB external HDD), via direct wifi connection or if you have PS+, via cloud save storage.
This is the same for all PS4 and PSVR that aren't one of these 10 games included in the list: you can use your PS4 savedata on PS5 while using them on BC mode.
But there are some games that are crossgen or got a remaster, so they have a native PS5 version. In these cases, it's up to the devs if they implement or not the PS4 to PS5 savedata import. If they do it (as it is the case in most games), you'll be able to use your PS4 savedata both in the PS4 BC version of the game and in the PS5 native version of the game. If they don't implement it, you'll be able to use your PS4 savedata in the PS4 BC version only, so the PS5 native version will have a different/separate progress.
The only 2 big games I remember that don't allow you to import your PS4 progress to their PS5 native version are Spider-Man (PS4) to Spider-Man Remastered (PS5) and Yakuza Like a Dragon. All the other crossgen games like Spider-Man Miles Morales or Sackboy will allow you to import your PS4 savedata to their PS5 native version. A couple of sports games only will import the progress in specific game modes.