Looks pretty good buttercup...
The white stuff can be a combo of White mold as well as aluminum corrosion from the casing of the old heater.
If you have not already done so - I would strongly recommend that you sand that would to a clean surface and then give that area a good coat of water repelant mildew resistant polyurethane varnish. There is evidence of black mold there - and although dormant now if you get any moisture it will grow and eat away at the wood - this is the stuff that does the dry rot damage - slowly unsuspecting death to the wood. A marine varnish application would be best - not sure what products you have in US but by the sounds of this forum you have tones to choose from and reasonable too. Save the old door! there is nothing worse than someone going to all the trouble of changing their water heater to have a "White" SOB door on the side of their A/S. Save that little grill too - Peter had to use that in order to modify as the new ones did not come with that little grill.
What is a "Blog" - is it just a fancy word for a website one is providing info on?? are there templates for a website you can add to or do they all have to be designed by someone - I have Adobe Go Live but have not a clue how to use it - but really want to make up my own little URL to sell our gargantuan number of airstream parts we will have - anything more than 3 things laying around will drive me nuts for sure....
Have really enjoyed your "Blog" - why I had an Aunt named Gladdys Blog....