Using CTRL+F and CTRL+G with Copy/Paste

Hello All! I've been spinning my wheels for two days now, so I guess it is time to ask for help. I have a spreadsheet (which changes every day) that has multiple rows and 12 columns. The goal is to figure out the number of unique "User IDs" (column A) and then split the work up between two people with each person getting the same number of users. I did the following in my macro:
Sorted the "User ID" column
Inserted a pivot table to figure see number of unique users
Used =COUNT(A:A)/2 to split that list in half
Used =ROUND(B2,0) to round up in case it was a half number
Used =CONCATENATE("A",B5) (I was trying to get a cell reference for the half way point
Then I did CTRL+G and copied and pasted the information that was output above...
Where this goes wrong, is in the macro, it uses the original value, for example A89, for each time going forward, instead of referencing that cell for the new go to, since it will change each day.

That was issue 1. Issue 2. After I go to the cell, I need to copy that User ID, go back to the original spreadsheet, hit CTRL+F and paste that information in there. Again, the macro records the original information. I would like it to complete a true copy/paste function each time since the information will change.

There are a few more steps, but those are the two I keep getting stuck on.
I'm sure it's obvious, but I'm fairly new to VBA, but I'm hoping I can get this to work, or maybe something else that will serve the same purpose. Any help is appreciate! Thanks for looking :-)

First off, thank you for your patience and instructions! It is appreciated, I'm very new to VBAs and Macros and am trying to learn more in an effort to implement efficiency improvements to a lot of burdened colleagues. I've attached a small sample, the normal sheets are typically 400 - 2000 rows depending on the time of year. There may be a much simpler way to achieve what I'm looking to do and I just haven't come up with it yet, so I'm open to drastic changes as well as the same goal is accomplished. Thank you again for the help, it is very generous of you!
waves678

Thank you, you've been very helpful!