Hi, sagarrajula!
About your code...
Consider uploading the sample files (workbook and database, even with dummy data), it'd be very useful for those who read this and might be able to help you. Thank you. Give a look at the green sticky posts at this forums main page for uploading guidelines.
About your questions...
1) Yes, you can. Besides, does this help?
http://office.microsoft.com/en-us/excel-help/use-a-shared-workbook-to-collaborate-HP010342985.aspx
Give a look at this file:
https://dl.dropboxusercontent.com/u/60558749/Userform%20Data%20to%20store%20in%20access%20...%20new%20database%20connection%20error%20%28for%20sagarrajula%20at%20chandoo.org%29.xlsm
Open it, click on command button, an empty userform will be loaded, just click on it and check column A: each time it stamps the actual date & time in first free cell.
Now go to tab Review (or whatsoever is its name in English versions, it's the tab from where you protect sheets and books), Changes group, click on Share Workbook, check Allow Multiuser Update and click on Accept, the book will be saved.
Then start a new instance of Excel (right button on a shortcut and select MS Excel from almost the bottom entry, or run another copy from the start menu) , open the workbook.
You'll have two copies of Excel running the same shared workbook, data in column A of both files should be the same. Adjust window sizes to see both at the same time, click on seldom command buttons to load the form, and begin clicking on each user form in a random way (x times on first, y times on second, and so on).
You'll notice that you can use the same form from the same shared workbook from two locations, but in this basic example there's a conflict on where to write the data, but if you use a DB connection and perform the proper validations it works.
Hope it helps.
2) A shared DB is a database placed in a network location that can be simultaneously accessed by more than one user.
Regards!