1. Shooting with 50mm lens can let you shoot at aperture as wide as 1.8 but a 18-55mm will allow you to shoot only at 5.0 aperture 
2. This difference itself is a huge deal. This means you can have the advantage of having faster shutter . Imagine shooting handheld at 1/15s with aperture f5.0 and then at 1/125s with aperture f1.8. This can be significant in low light conditions.

It depends on where are you uploading your pictures. Irrespective of the place, you watermark must be small enough not to cover much of your photo. You can keep your watermark mostly around bottom corner.  

LR Classic is basically what we all are used to what earlier used to be LR CC (Only Desktop based).

The LR CC is the new addition in LR list and is a stripped down version of LR Classic. Good thing about LR CC is you can sync your photos across devices (Desktop, browser, phone, tablet.)

But then the new LR CC has many new features missing. You don’t have Tone adjustments, Split Toning missing, Camera Calibration panel missing, no face recognition, no healing brushes, no upright tools,

BIG DRAWBACK: Adjustment History missing (OMG!!). if you are used to making HDRs and Panaromas in LR, then new CC lacks the feature. Heck, it even does not allow you to add Watermark on a photo. You will have to move the pic to Photoshop, add Watermark and then save (that’s a lot just for adding Watermark).

No Print Module-so you can’t work on collages.

Advantages of CC: Automatic Backup to Cloud, Sensei keyword tool- This will keyword your photos when you upload it to cloud. So when you check for any ‘lake’ photos it will list all lake photos, or you search for ‘kingfisher’, it may list all kingfisher bird. I can’t promise that Sensei will behave as it promises, but this is how it is supposed to behave.

LR CC: You can only save 1 TB of Photos on Cloud after which you will have to buy more space

LR Classic: Unlimited as everything is stored on your Desktop.

LR CC is good for casual Photographers who need to put images immediately from anywhere on social platforms...LR Classic is for a little serious Photographers

Any telephoto lens with focal length 200mm and above would be good. This is generic and affordable for most of amateur photographers. 

If you are willing to specialize in wildlife or willing to venture out in wildlife photography, can go for 150-600mm lens.

First question is that how do you understand if a lens is of high quality and will produce quality DOF (better DOF).

I'd like to explain DOF as not dependant on lens quality but dependant on aperture number (f-number). Usually low f-number lenses are expensive like 85mm f/1.4 is pretty expensive than 85mm f/1.8 costlier. f/1.4 lenses are also termed as better quality lens due to their internal structure.

Let's try one thing. Keeping ISO and shutter same, shoot at f/2.5 with 85mm f/1.4 lens then shoot with 85mm f/1.8 lens. DOF will remain almost similar irrespective of the cost of the lens. But if you want to produce even better DOF with either lens, you will have to shoot at f/1.8 on 85mm f/1.8 lens and shoot at f/1.4 on 85mm f/1.4 lens. Now you will find you the background is very much smooth in that image which was shoot at f/1.4 on 85mm f/1.4. So the reason is lower f number produce better DOF.

DOF is not the only reason to buy expensive prime lenses. There are other factors as well:

1. f/1.4 lens will be fast than f/1.8 lens.

2. Ideal for low light situation.

3. Better quality image.

If you find above points reasonable to invest large amount, can go with it. I don't think so until you buy lenses, can try new lenses at shop. Though you can get them all on rent for a day to experiment if you like the performance. Then you choose to go with.

If I'm hobby photographer, I'd prefer to go with f/1.8 lens as it saves a lot.

Reply for more queries on the topic.

You can use any lens for Bokeh Photography, Bokeh is defined as “the effect of a soft out-of-focus background that you get when shooting a subject, using a fast lens, at the widest aperture, such as f/2.8 or wider.” Simply put, bokeh is the pleasing or aesthetic quality of out-of-focus blur in a photograph.

A wedding i a magical event. It happens just once and so is it divine. It is the responsibility of the photographer to capture each and every sequence of this divine occassion in its true colour. It should not be all artificial, but it should have something that they do for the love of doing it. 

there are 2 ways of achieving focus

Using Autofocus

turn on the auto focus mode on your lens->then point at your subject->click shutter release button half way to lock the subject in focus->adjust your frame if needed WHILE HOLDING THE SHUTTER RELEASE BUTTON->press the shutter release button to take your photo with subject in focus

Using manual focus

turn on your manual focus on the lens->point at your subject->use the focusing ring to adjust focus according to your eye->press shutter release button to click the photo

Diwali season is on. Time to shoot some amazing fireworks. Have you ever tried earlier?

I use my gears Nikon D750 with 24-120mm lens to capture fireworks. I used the kit to shoot fireworks last year. One of my few clicks are attached with my post. Few things that are must for shooting fireworks:

• Any camera which can exposure for couple of seconds, say 1 sec or more.
• Having a tripod is beneficial to keep the camera sterdy and align along any direction.
• Having a wired or wireless shutter release will allow you to trigger the camera without disturbing camera.
• Right location. It's utmost important factor. You must know where are you going to get fireworks. I prefer to shoot at my terrace. I can point the camera in any direction.

One more point which may seam difficult for most of us but very important is the patience. If you are trying fireworks for first time, it will be little challenging for you so all you need to do it to keep patience while clicking.

Coming to settings, there are no ultimate settings but keeping camera exposed enough in time will allow you to shoot fireworks so shutter speed must be 2 sec or more. If you are not really sure about how long should you keep the camera open, you can keep 5 sec or more depending on amblient lights around. If amblient light is low, you can keep much lower shutter speed. It will allow you to capture any moment in the sky.

Aperture would be good if I keep 5.6 or higher in number. If you still believe that you are getting very low intensity of fireworks, open the aperture. Reducing shutter speed here will not help. Keeping lower shutter speed will bring light trails in the image. So if you are getting good trails but low light intensity, need to widen the aperture.

Similarly if you are getting light intensity too high, need to reduce the aperture. It will cut down the extra light. 

Let me know if you have any points to mention to discuss. Do post your questions in follow up posts.