Will the 16gb iPhone 6s be enough? Can iCloud

I pre-ordered a 6s plus (16gb) because i finally wanted to upgrade to apple. Then I realized how little 16 gb can be.
With ios 9 there's supposed to be "app thinning" but its still a small amount. If i were to pay the monthly $0.99 for 50 gb of storage will i be able to keep photos/videos there and delete them from the phone? (again I've never owned an iPhone so I'm a bit apple ignorant). I don't really have the extra money to go 64 gb(though I'm trying to accumulate the funds…).
Would it be better to stay with the 16 gb with iCloud, assuming it works the way I think it works, or wait and save for the 64 gb?
I'll probably keep the phone for about a year.so 12 months of iCloud = $12
64 gb = $100 more

16GB is absolute poverty-specification. It's what I had 5 years ago on my iPhone 4 and even then it soon became frustratingly little.

iCloud storage is useful, but the data stored on it only then becomes accessible when you have a good data connection; when you're away from home/school/work that can be very frustrating. It also means that when not using a Wi-Fi connection you're sending and receiving far more data to and from iCloud, so it can eat up whatever monthly data allowance your phone plan includes and you then start getting charged at fairly high rates for additional data, so your $12 per year may be rather higher than you expected.

Finally, iPhones traditionally have excellent resale values after one year. But a 16GB version won't as few people will want it and in another year's time 16GB will be even more useless than it is today. It also doesn't help than modern app coders/software writers have become very sloppy and lazy and increasingly use immense amounts of storage to do things which I used to have to achieve with a few bytes, simply because these days memory and storage capacities are typically immense and very cheap.

64GB on an iphone 6s+ is the bare minimum you should be considering for a private usage phone, and even that's likely to become a bit tight over time. 16GB is really only suited for usage as a corporate phone where employees are forbidden to add their own apps and personal data, and where the corporate buyer can save immense amounts when they bulk purchase by keeping the phone specs to the minimum they require.

Although the screen is smaller, a good used iPhone 5s 64GB is in almost all practical respects every bit as usable as an iPhone 6 and is far cheaper. We've yet to see how much more useful the upgrades to the camera, processor and the introduction of 3D Touch are on the 6s and 6s+.

One final point against iCloud: it is incredibly useful even on a top-spec iPhone as it allows iCloud backups, but the more you use it the more you invest in Apple. That makes it far more difficult to switch to a competitor later on. You do get a limited period to download all your data if you ever do close your Apple iCloud account, but most people find it to be awkward and time-consuming and have a fear that in the process they'll lose something irreplaceable.

In summary, save up for longer and get at least 64GB, or be a more canny buyer and make a large saving for little sacrifice in performance and buy a good used iPhone 5s 64GB or perhaps a used 6/6+ 128GB.

I only use 16 and its fine for me, but I don't dump a bunch of music on my iphone and I offload pics I want to keep to my computer, if you don't keep piling up garbage then its fine.

Keep in mind also with iOS 9 Apple shrunk iOS from 4GB to 1GB, which is pretty incredible, so you gained 3 GB more. In comparison, a samsung has 8GB taken on it so that 7GB more bloatware.