Regarding 7-Zip, if you have 64-bit operating system, install 64-bit version, otherwise get 32-bit version. You can check that information by right-clicking Computer in Start Menu and selecting Properties. You can always try 64-bit version first and if it doesn't match, it won't install at all.
The game I have on Google Drive consumes 347 MB of space, it was a little larger before today. So that's how much you actually download, for some reason, downloading files off Google Drive doesn't show the file size so you only see it when it's finished downloading and for the same reason, you don't see how much time is left until it's downloaded. The Google Drive links for both the full game and the patch itself are always the same, so if I update any file, the same link will point to updated file. When you unpack the file with 7-Zip, the unpacked Drakan folder consumes 567 MB of space.
Another thing about 7-Zip, if I remember correctly, it doesn't alter any file associations by default, so unless you open its settings and make some changes there, you can open .7z and other types of archives by right-clicking on the file and selecting the desired option in the 7-Zip sub-menu.
You said you ran System Restore and you now have freshly installed game that is at version 445, correct? If so, if you extract my version on top of it, that will bring it to version that's patched with AiO Patch and contains tons of player-made levels. Then you'd just need to run Disable_Drakan_Compat_Fixes.reg from AiO Patch ZIP to prevent Windows from blocking alt-tabbing when you're in the game.
Also consider using dgVoodoo 2 from here
. It can improve performance, especially noticeable if you set Max Fog Distance to 200% in game's graphics options menu. This increases the visibility dance for all stock levels except Ruined Village and Volcano which haven't been updated yet.
There is extensive documentation on its website, but basically, you just throw DDraw.dll and D3DImm.dll files from the MS folder in the ZIP to Drakan's folder and see if it works. And since you're on Windows 7, you also need to download D3DCompiler_47 from its download page and extract the file d3dcompiler_47.dll to Drakan folder as well. And just in case your Windows installation isn't updated, I think installing Windows 7 update KB2670838 might also be needed. Unless your graphics card is very old, it should work OK.