1: use https://www.macrium.com/reflectfree
2. your windows and everything u cloned will be exactly the same
3. Depending on the size of your new ssd , if its just 128gb ssd then i recommend deleting everything except windows before cloning from your HDD to new SSD. If ur ssd is big enough then u can just clone everything to it.
4. The best way to make sure nothing goes wrong is after cloning unplug your old HDD and go bios set new SSD as primary boot drive then start your pc. If it works then plug in your old HDD back then delete the windows files on it (recommend format the whole drive so there wont be any conflict , u may save your games etc to external HDD)

u can google how to clone with macrium reflect.

u can keep windows file in your old hdd , the reason for formatting old hdd is to prevent any conflict between old and new windows files. Once your new ssd starts up windows normally there shouldnt be any problem and u can safely format your old hdd.