Regarding the UV filter...Yes, I agree with Onlsow on this....it won't protect from a fall or good bump.  I also don't like the idea of another piece of glass in front of the lens....BUT in saying that, I DO use one most of the time...LOL.  It does give me some protection in case of finger prints, water spotting...or accidentally hitting a leaf with sap while taking a macro....

Regarding the lens hood....I know I should use them...but I find them to be a pain to put on and then reverse for storage.

Regarding the use of a free hand to block the light source....hasn't worked for me...I'd need to be an octopus....

One final comment on UV filters....Do NOT use them to take Aurora photos....I found this out the hard way...they create an interesting effect that resembles Newton's Rings on your image.  I  had this happen on my first attempt...thought the filter was touching the lens...NOT...Tried again loosening the filter thread..same thing. Tried without any filters...no rings.
 I did some research on the web and found others having the same result...something to do with the frequency...I'll see if I can find the link again.

In youth, we learn....with age, we understand.