You make a system image of the hard drive, not a specific account. The advantage of a full system image backup over System Restore is that System Restore only saves specific windows files and the registry. It does not save anything else and many times the files System Restore saves are not the cause of a problem. Restoring a system image will put you back to exactly where you were when the image was taken.
There is nothing wrong or unusual at all about running as Administrator. This is the account set up for most owners when you set up your computer. You sound like you know what you are doing so you can likely trust yourself.
I would not run any tweaking or optimizing programs with Win7. It will always come back to bite you. Win7 is already optimized and as lean as an OS can be.
Since you asked about cleaning up bloatware, here are some tips based on hundreds of factory bloated computers I've helped clean up: HP laptop has used up all four primary partitions
PcDecrapifier does a reasonable job of getting rid of a lot of the bloatware. I've used it many times on XP systems. Says it work for XP, Vista and Win 7.
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