Simple BAT file to copy files to specific folder

Hi All. I need to do a cleanup on a computer and basically copy certain file formats into I would assume one folder.

I was going to use something like this as a simple starting point:

@ echo off
COPY "Source folder path*.xlsx*" "destination path"
PAUSE

A few questions:

1. What is the seperator for file format? For example if I want to copy excel and powerpoint files (In my case it will be different photo types so jpeg, png, mov, all those type extensions) is it the comma or semi-colon seperator between extension types?

2. If I want to include sub folders in the source folder path (Eg. desktop has a few different folders and sub folders, want to extract all files of specified format to one new destination location)

3. Thirdly and this is probably strange… If I want to copy the files and sub folder they are located in. So for example if I have desktop1 and desktop 2 folders, and both contain excel files.. in the destination folder I would like these sub folders to be included and then the file inside this folder, so within destination folder desktop 1 and desktop 2 exist with the relevant files within them…

The reason for this is there are probably duplicated files and folders, in fact I know there is because the person is unorganised so there will be multiple duplicated files and folders. By copying the sub folder that the file is contained within I can then run the script again with a specified source folder (desktop1 folder may exist in a few different locations on the C drive but using this I can bring them to one location then run script again with specified source folder path), and then bring the files back into one folder The only issue I can see with this is it won't copy the same folder name into a destination, if it already exists so is there any work around, or different approach or ignore duplicates of the destination file itself of same name. I don't really want to over engineer it to be honest although this point 3 sounds complicated!!

4. If I do proceed with point 3 above, there will be a lot of files and stuff going on! Is there anyway to add a time out or pause or break because the speed the copying takes will lag significantly vs the speed the script rune at and will this cause a crash or fatal exception or issues in the process? Is there a way to add a break after every say 100 files press enter to continue or something like that?