. . .my balance is showing as 5.0e-05 (not quite sure what that means. . .
That means you have 0.00005 BTC (about $0.000625); a small amount.
. . .Does the 5 before the . indicate 5 bitcoins though, do you know?
No.
The 5 indicates that there is a 5 somewhere in the number. The
e-05 indicates that you need to move the decimal place 5 places to the left to get the actual number (It's called exponential notation
http://en.wikipedia.org/wiki/Exponential_notation ).
So it is indicating that you have 0.00005 bitcoins. That would be 5 hundred-thousandths of a bitcoin which as a fraction simplifies to a twentythousandth of a bitcoin. In otherwords, you'll need twenty thousand times that amount to have 1 bitcoin.
Perhaps you've seen the number written as 5.0 x 10
-5