Look on the web and take the rate that most interests you, to give you an idea, 60 gigabytes of download are around 38 euros per month, and with these data, I think they are more than enough to watch Netflix at home, see Youtube videos and have a normal life with internet, but time will tell you if you need more or less data.
It i obvious to say that these rates are continually changing.
When you receive the SIM at home, you must remove the initial security code of your phone, to do this, go to SETTINGS, look for the SIM LOCK option and deactivate it.
Once done, write to your SIM SELLER (in this case , www.somos4g.com) and ask them to activate the card.
As soon as they send you an email confirming that the SIM is active, insert the SIM in the router, and you just have to turn it on, you will finally have WIFI internet in Casalonga.
IMPORTANT
If your internet access is sporadic, save all this and create a portable WIFI network point with your mobile phone, activate it, put it close to your computer and connect to internet without problems, it is another fast and cheap option.