glad to hear things worked for you!!
ok, for the 1st question, the answer is:
simply, no. you need to modify users groups after creating them. like this:
to add an existing user to a group use this command:
usermod -a -G groupName userName
you can check here:
I think this guide will help understand things better:
for the 2nd question, yes, it is a bad practice, but only for one reason. if you don't have that folder on your home tree folder, that user may not get into function. so the system is going to consider it invalid user.
so it is better to change it after changing the user folder name. you can do that like this:
mv /home/user/oldname /home/user/newname
make sure there is one space between these two paths.
you can check it out here:
then you can look at your /etc/passwd to see if changes took place or not. if not, possibly you need to reload your system by logout and login to see the changes in effect.
no need to logout from puTTY if you use it, just open new puTTY console and see if things changed!!