I have seen carry -ons bigger than mine (21-10-13) on KLM and Air France....no one payed any attention.

In well over 20 trips in the last decade, on many airlines (including KLM)I have never had to check a 'roller bag' on the way OVER. I always make sure my bag is no more than 21" including handle and wheels, and I weigh it to make sure it meets the specific airline I am flying weight restrictions. Occasionally they will weigh it at check in, even going from the US. On the way home it can be a different story, they are more likely to weigh it. However, as you say, I don't care that much on the way home. I have traveled with people whose 'cabin size' bag is 22" or even more with handle and wheels and they have had to check it, even on the way over. I think the key is that it be on the safe side of specified size.

For the 'personal item' I usually carry a back pack or tote bag that looks a lot like the one in your link - because they are 'squish-able' they do fit under the seat and I have never had that questioned. I try not to have it too bulging (for example I might put on a sweater or shall or something instead of putting in the bag if it makes the bag look huge). Very rarely (although it has happened) is that one weighed so I put all the heavy stuff in there to make sure my main bag meets the weight limit.