Im thinking of getting an SSD in the future. If i bought a windows 7- 1PC would i be able to install windows 7 onto the ssd even though i already installed it to the HDD or would i have to clone it from the HDD to the SSD
OEM copies of Win 7 is tied to the Hardware, so technically you need to clone, but if I recall correctly, it only checks the motherboard, so I suppose you don't.
You shouldn't encounter any problems with reinstalling. At worst the program will require a phone activation instead of online. I've done something similar. The main reason for it is to discourage pirating.