Yes, it is, but devs are a bit busy on their projects, be patient 
If you won’t use some feature/service, don’t use/install it.
Well, it will depend on the use case, the concurrent users, etc. but usually you won’t notice any performance issue when using quotas or when vsftpd is installed… but as I said, if you are going to use a low resources VPS, don’t install anything you won’t use.
Cheers,
sahsanu