I hear you about painful experience.
Thank you for the info about contacts in icloud and migrating to outlook. I didn't use icloud for contacts, calendar, or notes.
I used outlook for those (contacts, calendar, or notes). Then in itune settings I set to sync with outlook for those 3 and not use icloud.
I found the 1st time I tried to start using icloud for contacts and notes icloud truncated contacts and notes to about 250 characters.
In the actual "outlook contact" notes section I had pages on some. When exported outlook contacts to sync with icloud I lost a lot of info.
So I rolled back to just using Outlook again for contacts, calendar, or notes. The downside was I would need to have my PC and phone together to sync and it wasn't backed up in the icloud.
After many years I did eventually give in and started syncing with icloud for everything. The lengthy contact notes weren't a priority compared to the convenience of always staying updated and backed up to icloud. Syncing with i-Tunes over the years was
always a challenge and buggy.
Generating the app RSA type key for Outlook on apples site did allow me to create my apple email account in Outlook. But I too noticed the icloud email contacts and calendar wasn't showing up in outlook as it used to in older versions of Outlook. I ran out
of time and had to go to work and haven't attempted to fix that issue yet. I will this weekend.
Your question about Gmail integrating with Outlook. I have never integrated the two just because I don't use Gmail but I do have a Gmail account so I did just try to add Gmail account to Outlook. I was successful adding Gmail account to Outlook 365 with
very similar way as we did with icloud email account. I logged into my Gmail account online and under "Security and Settings" I turned on 2 step authentication then created an app login by selecting "other". Named it outlook then selected button to generate
RSA type key. I copied the key from gmails site and pasted in password section when creating gmail account in outlook 365 and it did work.
I'm wasn't sure if your question regarding integrating gmail with Outlook was doing the above paragraph but thought I would mention it.