Upgrading postgres to 10 from 9.5 using pg_upgradecluster

[Debraj Manna <subharaj.manna@xxxxxxxxx>]

I am testing the process of upgrading postgres to 10 from 9.5

I am following the steps as mentioned in this link -

dmanna@ubuntu:~$ pg_lsclusters 
Ver Cluster Port Status Owner    Data directory               Log file
9.5 main    5432 online postgres /var/lib/postgresql/9.5/main /var/log/postgresql/postgresql-9.5-main.log
10  main    5433 online postgres /var/lib/postgresql/10/main  /var/log/postgresql/postgresql-10-main.log

sudo pg_dropcluster 10 main --stop
sudo pg_upgradecluster 9.5 main -m upgrade
sudo pg_dropcluster 9.5 main

Can someone let me know the following

1. If there is a way I can check if the upgrade will be successful before going for the actual upgrade? 
2. If I am using the link option in the upgrade can I still use the sudo pg_dropcluster 9.5 main?