Is there any rough framing of what ivlvs are suitable for different m+ levels? I understand that it depends on the person who has the key - will they invite or not. But what ivlvs are needed to perform well on certain levels? For example, when should you start going for +7?
It depends more on your presonal skill than your ilevel. There are individuals that with 610 can perform on a +7. Others with 680 have trouble on a +7.
As for getting invited: A) Play your own key. Dont forget. And B) It depends a lot more on RIO than ilvl.
When it comes to getting invited to keys: ilvl is only really relevant in extreme cases, like my alt that is 606 doing M+… or, really early in the season (like first month or so).
The rest is RIO. So I would focus on going key by key. Start by doing all keys on +2, then +4, and so on…
Hard to answer that, since keep in mind that people were farming 10s at the start of the season with 638ilvl from previous season.
ilvl is not that important, as actually knowing your class, and being able to perform both the dps rotation but also use interupt/cc/defensives when needed for dungeons.
Now if you are talking about pugging, ilvl is secondary to rio, and rio gets you through the door, but experience is the thing that will get you through the dungeon.
My personal opinion, get in groups with high rio players on their alts, and try to understand what and why they are doing stuff. The biggest barrier is is knowledge and experience in this game mode, and frankly ilvl will not make much of a difference compared to the knowledge gap.