I have done this multiple times back when I was getting greedy/ careless while racking and wanted clearer beer.
A piece of advice though, boil the water you use to make gelatin and allow it to cool to the 160 F or so that you would normally mix the gelatin at. This will remove O2 from the mix...
I have my second batch of the Zymurgy recipe bubbling away as we speak. The first batch was very well recieved and didn't last long. I used 7 lbs 2 row and 6 lbs M.O. as it was what I had available and I wanted a bit more malt backbone. I will be dry hopping my current one with 2oz. Centennial...
15 minutes should be fine. I don't believe you will have the same problem if you boil the "extra wort" prior to storage and it should be fine when you boil again to use it. I think it is difficult to get a vessel 100% sterile but it probably depends on your methods.
I may be at an advantage as...
Do you boil the wort collected prior to storing? The mash is not a sanitary environment and the runnings will not store well if they have not been boiled for a short time.
To control the speed of an AC motor you need to adjust the frequency of the power supplied to the motor. The easiest way to do this that I am familiar with is a drill press/ router speed controller (see below) but this may not work for such a low power fan, I am guessing this is the issue with...
I have done this on my last few beers including a version of the IPL in the link below altered as described below.
I use 8oz of water per 1 oz of hops at approximately 170 F, I find that at 8oz I get a dense easily poured light slurry . I will let this sit for 20 minutes stirring occasionally...
I like to add de-pithed peel from two oranges in the whirlpool of my Hefe. I usually just use an apple peeler to get the bits I want and leave the less desirable parts.
... as with the others I am going to have to try a Hefe with Rye.
I just wanted to add that the best hefe's I have had...