Hi,

I'm a relatively knowledgeable Excel user and I have many repetitive, but complex, tasks that I do on a regular basis within Excel. Thus, I was wondering if I can look into recording/using macros in my situation. Since I'm a business owner and I "live" in Excel, I need to be 100% sure that in looking at this option will not cause any harm to my business-critical Excel files...I run my business from Excel and need to be in full control of everything that happens within the workbook(s) and have the ability to find issue (in macros) if they arise. Let me briefly explain my situation:

- I currently use a PC and use Excel 2010 and use 1 primary file (with many data points referencing various parts of multiple tabs). This "master" file is saved as .xlsx (and I want to keep that file extension for sharing purposes). I create this "master" file from a weekly template that I change with updated data from other information sources.
- I email parts of this file (saved independently) to: (1) a co-worker that uses Office for Mac 2011 (she does NOT want to use macros, (2) other people in the company that are novices in Excel (and I don't want to confuse them by saving the file as anything BUT .xlsx, and (3) suppliers and other recipients outside of our company that wouldn't have any idea about macros.

Here are my questions/concerns:
1. I want to keep the "master" file extension as .xlsx (not have it as .xlsm). Can I do this?
2. As a follow up question, I think I would do this with a Personal.xlsb workbook (in which I think would save all the macros for me to use across multiple workbooks, without saving macros to a specific workbook). I want to have macros available across workbooks. Is this the correct way of accomplishing what I'm looking to do?
3. I want to make sure that any macros that I save on my computer could only by accessed/used by me. In other words, I don't want anybody that I email "independently saved" parts of my "master" file to (co-workers, suppliers, etc.) see what macros I created for my own personal use. How can I do this?
4. Any other advice to someone that knows Excel pretty well, but is new to macros?

Any thoughts about starting with macros would be greatly appreciated. Thank you very much in advance.

Yury