save a file with serial numbers following the last file name in the folder

Hi, 

I regularly scan images through a scanner to photoshop and I use them for different purposes

I want to create an action to automate the contrast adjustments and then to save the file to a folder 

My need is to save all the files in a particular folder and I have to make it everyday now and then 

The problem here is when i make it through actions it overwrites the old files 

|I want to make any one of three things 

1. When i'm importing a document from a scanner the file name should be generated with the current date and time like how cameras generate filename

Example :   "2020-01-27-10-09-20.extension" or "20200127100920.extension" like year-month-date-hours-minutes-seconds

2. When saving an untitled document it should save the file with file name as same format as above

3. when saving file the name should be a 4 digit serial number and the number should be the one which is next to the file name of last file in the folder

Example : 

If a folder contains a list of files with 4 digit serial number names

2401.jpg

2402.jpg

2403.jpg

2404.jpg

2405.jpg

2406.jpg

2407.jpg

2408.jpg

2409.jpg

2410.jpg

2411.jpg

2412.jpg

The next saved file should be saved with name "2413.jpg"

Please Suggest a way to automate this

And i have no clue about scripting

Thank You in advance.    🙂