I assume you do not have the old type with the ball in it, it is probably as stated low battery or defective mouse. I usually have to replace mine about every year.
Welcome good to see that you have positive out look. Good luck to you on your journey.
For shooting macro I would recommend using either manual or aperture priority so you can control your aperture. As Linda said do control settings and change one thing at time so you can isolate your problem do not change several settings at one time just one at a time.
It looks like from my monitor that depth of field is part of the problem. What aperture are you using. Also your focus point does not look like it is on the blossom. Are you hand held, the focus point at that close is hard to get some times as a minute movement and a shallow depth of field can be a problem. A faster shutter speed also might be needed. Macro and close up is a challenge, but with study and practice it will get better. I try to use a mono pod or tripod when possible or continuous shooting.
I am also left eye dominant, have been all my life. I shoot left hand which can be a problem with semi automatic weapons. I have not had any problems use my left eye. The only way I can use my right eyes is to shut the left eye or cover it. I am some what ambidextrous as there a several things that I am right hand dominant in writing. As fare as tools it depends on the tool it seems. There is advantages at times but you do adjust. It just takes some time and patience's.
If you are birding for instance, to get a good detailed shot the closer the better even with 150 600 lens. A humming bird at 20ft. is still tiny so I like most shoot so the bird fills the lens even when up close. Most wild life I like to be as close as possible. Flowers are another good example of being close.
I would straighten it. As Linda said the distance memorial is where you end up looking at as the leading lines attract to the memorial and that is actually the focal point. By the way a outstanding composition for me liking.
It looks as if you were under exposed. In Raw you can increase exposure as you did but you will probably be under exposed in the shadows. Your polarizing filter depending the type that you have can be turned as you described to make the sky darker and or more blue to keep it from being blown out. If you hold your filter up to the light and rotate it you can see the difference as you turn it. You need to google or go to youtube and read up on filters. You will loose one to two stops when using it so remember that when using and over expose accordingly.
I have the lens, probably my most used lens as I like to keep one camera set up for macro. I have it on my 7d a high percentage of the time. I also use it on my 5dii but I like the focus system on the 7d better, it is faster and seems to be more accurate. Maybe it is just me but my 7d has always been my favorite camera since I went to dslr which was about 12 years ago. When acquired the it and learn to use it focusing system it has been my stand by.
No. #2 is a great comp for me, leading lines are great use of subject.