Absolutely correct. This IS the easiest solution. The only rejoinder is to consider your alotted disk space on the free site (some of them are pretty restrictive). In other words, your pics cannot reside there permanently, but must be swapped out before storage capacity is exceeded.
Good point. However, Netfirms gives you something like 15 Mb of storage and there are others that give you up to 25 Mb. I have about 40 good pics on my hosting service (free) that I link to occasionally and I'm only using less than 2 Mb currently.
There is no doubt that you need to read the fine print to see what their limit is and also if they even allow linking. Some don't.
I had to try out 3 or 4 before I found one with no adds and really fast servers with 20 Mb of storage.