How do you search by user if I don't know their user id? Different user, not myself.
And why doing a search like 'user:fgfgfblahblah apples' returns a ton of results when fgfgfblahblah doesn't exist!?
At http://stackoverflow.com/users, there is a search box where you can search by username. Once you have clicked through to the user profile*, the number in the URL bar is the user id.
*You can also reach the user profile by clicking on the user's username in any of his/her posts.
The reason is that searches are done using OR searches, so it returns any results where the word
No idea on the second part, as for the first... I would try to find their ID.
Either find any post by that user or Click users and then type their name in to search.
Once you have a hyperlink, hover over it and copy down the number.
Go to the User Page
Search for their name
Click on their name
In the URL of the page you are directed to, the big long number is their user id.
For instance, yours is: