Defrosting?

I have defrosted in the microwave and left the loaf at room temperature. Both worked well - I always remove the bag the bread was frozen in. I've heard the worst thing you can do for bread is to keep it in the fridge, but Idon't know why . 

My understanding of the science of the staling process is that the regular temperature of a refrigerator is that it's exactly the temperature you want if you want to stale your bread most quickly.  I think I read this in Bread Science.

I slice my breads and store them in a plastic bag in my freezer.  I then place them directly into the toaster.  Be extra careful with the microwave as over-microwaving is the direct path to making shoe leather, in my experience, not in yours?

When necessary I freeze whole loaves and then thaw them on the kitchen counter.  If I'm in a hurry, I will thaw them faster, enveloped airtight in aluminum in order not to dry out the crust before the crumb (innards) thaws.  I do this in a medium oven if I'm in a hurry; a lower temperature, if not.

I've always had the best luck defrosting storebought-style loaves at room temperature by leaving the bag closed. When you freeze the bread, some of the moisture will come out of it - thus the inside of the bag may be cloudy or even host some ice crystals. When thawed, water needs to go back into the bread or it will be noticeably dry/stale. 

How to figure out the exact right amount of water? Well you've already got the exact right amount, the amount of water that's inside the bag. Just leave the bag closed until the bread is fully thawed so you don't evaporate away some unknown quantity of water.

There is an alternative; it works especially well with thick-crusted breads that don't lose much moisture when they're frozen. Here it is: take the still-partially-frozen loaf out of the bag, mist it a little (just a tiny bit of water, not wet like a sponge, maybe just shake wet fingers over the loaf), and put it in a heated (350F ?) oven for about ten minutes.This finishes the thawing process, re-crisps the crust, and drives that tiny bit of moisture back into the crumb. Depending on the style of your particular loaves and your taste, you may need to adjust the pre-thaw time and/or the oven temperature a little next time. (I've never done the experiment of doing this with storebought-style loaves that have a very thin crust and/or exude a lot of moisture when frozen, as I expect it would fail miserably:-)

When you decide to freeze your bread, make sure you store it in freezer bags, not just the typical plastic bag/wrap you might otherwise choose when puting food in the refrigerator.  Plastic wraps, other than those designed specifically for freezing, are porous enough to allow for some air to pass through them.  Even though the pores are microscopic, they can allow enough air to pass to cause your bread to dry out.  For other foods, using low grade plastic bags/wrap sets up an environment for more rapid freezer burn.