Upgrade Inspiron 15R SE (7520) with SSD

I would like to buy the Inspiron 15R SE notebook and replace its HDD with an SSD. I have some questions:

• Does it void the warranty if I replace the HDD with an SSD?
• How can I know whether a certain SSD is compatible with the notebook? Or any 2.5 sized, SATA2 or SATA3 SSD is compatible?
• The Inspiron 15R has a SATA2 port, for which the maximum transfer speed is 300 MB/s, right? So there is no point in buying an SSD which has faster transfer rate, am I correct?

Thanks for any help.