For someone who describes themselves as an HDR beginner you are certainly starting off at a very high standard. You seem to have grasped right at the beginning that HDR is about retaining the details in the bright areas and bringing out the details in the shadows while at the same time retaining a full range of contrast. You have also picked perfect HDR subjects.
#1 Really nice pic with very effective B&W conversion, very crisp lines. You do have some haloing to the right of the windmill and above the tree on the right. Moving the smooth highlights slider further to the right, changing your lighting mode and possibly pulling back on the strength slider just a tad should reduce or remove the halo. You also need to adjust your horizontal as the picture slopes down on the right. Once that is done you then need to adjust your verticals as you have some perspective distortion. But these are minor issues on an otherwise lovely piece of work.
#2 I like the processing as it really creates a pic with impact. The sky is fascinating but you should probably have pulled the blacks back a little. You have also got a couple of blown areas in the sky above the right hand sail and on the wood of the window frame in the bottom right. If I was to give my best pieve of advice to anyone starting out in HDR it would be to avoid blown highlights at the HDR merging stage, you cannot recover them later without a lot of fiddly cloning.
#3 Nicely controlled light with a pretty good DOF. But again your horizon slopes down to the right and there is a touch of lens distortion as the horizon is slightly curved. Both easy fixes in PP.
#4 You have avoided one of the biggest problems with boats and that is that the white hulls tend to be highly reflective and very easy to and up with blown highlights. The HDR is well done with good control of the light. But you probably need to boost the contrast a little for the orange boat. HDR tends to lower contrast so tweeking up the contrst a little should always be part of your workflow. As a composition I am not quite convinced that the crop works as there are a number of chopped off boats and jetty areas. I know the lifeboat is the subject but I think that it might have worked a little better if you hadn't chopped off part of the lifeboats mast. But that may be down to personal taste so others may disagree.
#5 Again a really nice subject, full of interesting details. But I don't think you have controlled the light quite as well as some of the others as there are some intense whites and a number of darker areas where detail could have been brought out. The structure on the bottom right for instance has blown and the curved area at the far end of the wall is very dark and featureless. Again the pic needs straightening and the perspective distortion needs adjusting.

As you read through this you will have realised that I am a very picky pain in the backside but the reason is that I am passionate about HDR and clearly you have a really good eye for it. So please take my pickiness as a compliment and also as encouragement because I think you could be very good at this genre. You will get many well deserved compliments here but the challenge is to keep improving despite the compliments. I really enjoy your work and look forward to seeing more.

Peter