Ok, being a creationist and future scientist here's my explanation:Yes humans and gorillas have similar DNA. If you take a look at all of the organisms that inhabit earth, organize them from the simplest to the most complex, you should find that there are alot of creatures with similar DNA.
I personally believe this is due to the result that a higher power created things in order, taking things from the prior creation and adding and changing some things in the process.
In the case of the bacteria, yes they do evolve (and quite fast since their reproductive rates are so rapid). I believe that a higher power endowed the creations with the power to adapt to their environment, hence the ability to evolve.
How's that?