Do you want two separate workbooks? or can you add a separate worksheet in the same workbook to handle your checkbook?  I would think that if your checkbook can be handled on one page, then it can be a separate worksheet in the same workbook.  Think about it.

I've been using my budget on a spreadsheet over at least 10 years. I will say that my budget has been a work in progress.  I started one, then adapted and changed it as I saw the need.  So, don't worry if it isn't "perfect" for the first try.  Start one.  Use it for this year. At the end of the year, take a look and see what you would like to modify.  That is what I would do. 

As for categories, they need to be what works for you.  Here are the categories I use:  housing, food, clothing, utilities, vehicle, charity, entertainment, gifts, personal education, investments/retirement, and miscellaneous.

I do not have a separate category for medical expenses - I don't have much in the way of medical expenses.  If you have a fair amount of medical expenses, this might be something you will need. I think you definitely need a "miscellanous" category - or something with a similiar name, to catch all those expenses which don't fit anywhere else. Another category you might want to consider is "cash".  This can be used for anything you spend pocket cash/change on. This can help to account for "nickel-and-dime stuff" which you buy, but you don't want to track individually.

One thing you might want to do is to look at your checkbook, and see where you write checks out.  This might give you an idea of what categories you will need. 

Remember, at the end of the month, income has to balance with outgo.  If you are spending pennies, nickels and dollars out-of-pocket, and you don't account for them, it can really screw up your budget.