Welcome to the forums perroloco

First of all your choice of hardware upgrades are good however I would go with cheaper ram because you won't benefit from the extra speed the vengeance RAM offers as it will run at the same speed as the other two modules which are slower. So you may want to look for some cheaper RAM, however, this vengeance will still work well. You will be able to upgrade the two modules and hard drive without voiding your warranty. Just remember when upgrading the hard drive though that you may want to make sure that you have a copy of Windows so that you can install it on the new hard drive. It might also be possible to clone the current windows that came pre-installed on the stock hard drive but it's better to install a fresh copy. You can just download the copy of windows and use the key that your machine came with, no need to buy windows again.

You can also purchase the laptop from websites such as Newegg or eBay if you are getting it shipped to the US.