How to increase laptop RAM?

Question

RAM

I have a laptop vaio sve1712s1rb , now there is a bar:
AIDA shows the following picture:

Question number 1: what is the real frequency of RAM?
Question number 2: on the official website it is indicated that

Max. support memory (GB) 8

although AIDA says something else:

Question number 3: To increase the memory to 8 gigs, is it better to put one on 8GB or buy in addition to 4GB?
Options , for all the advice I will be grateful!

Answer 1

Cheaper and easier to buy another 4 GB stick.
If you want to buy a bar for 8GB, then maybe 2x8 up to 16 right away?

Answer 2

AIDA can dance from the maximum size of the bar, and DDR3 SODIMM has exactly 8,
so it's better to trust the site