Can Google Chrome installed & Google Chrome portable both be used on the system or this could generate issues?
Yes you can use both (I have for years). I use the portable version when I want to test site compatibility or the browser without any extensions running. I also have Firefox portable installed for similar reasons.
Installed version I use for everything. Portable version, no extension & only for banking & online shopping with Lastpass.
Why would you trust the lastpass extension with your credentials over other extensions in a browser which apparently has privacy issues.?
I am fine with Google Chrome. Portable Chrome with Lastpass extension only is faster compared to installed Chrome as installed Chrome has quite a few extensions as the system is a family system & shared by others.