Typically a business plan is only necessary when you are looking for investment, either equity or debt. Personally, however, a five year plan can help you focus your direction and vision for how you would like your business to grow. If your business currently has a lot of positive momentum and is growing a plan can help you to determine the best way to grow to maximize potential gains from the growth. You can also easily share a plan with other people to get them on board helping you with your plan.
Financially speaking there is nothing wrong with a loan if you can use it to make more money--it's called leverage. You can read about it here:
http://en.wikipedia.org/wiki/Leverag...ncial_leverage
Of course you take on greater risk to the firm by taking on debt, but the risk is mitigated by having a clear plan to return the debt invested in to greater profits to the firm. This is why banks require plans during the loan application process.
Hope this helps! It sounds like you have something good going.
