Hi Erling,
please have a look into manual (chapter 3.3.3 Certificate Management).
Check page 65 (Title: Create SAP Server Certificate).
Even if this step is described for SAP Server certificates, this configuration step can be used to create user certificates too.
Export this certificate in P12 format and import in your client PC (Windows Certificate Store).
I don't understand your second question with max. 7 days valid certificates.
Maybe you can provide a screenshot?
In Secure Login Server Certificate Management you can define with the paramter Valid From and Valid To how long the certificate will be valid.
Best regards,
Frane