It will return hashes, it'll simply take a longer time (also means your effective pool hashrate will fluctuate a lot more).
Assuming you're mining with an Antminer S9, you'll get a share every 5-6 minutes (on average).
It never did. I had it pointed to port 4334 for a few hours and then back to port 3333. On port 4334, I was getting an error message that my diff was too high. On port 3333, the diff was too low. I created a support ticket and was able to get almost 100% refund.
This quote is from one of the admins from MRR:
"We do have to pay the rig owner for the time that the rental was elapsed. This rig owner does well on his rigs, you can see the rig's history is stable. Your pool choice did not work, we do not give refunds for pool related issues.
If we gave away full refunds everytime a renter makes a mistake, we'd go bankrupt really quickly.
I'll issue a credit this time, but we expect the investment should be worth while.
Thanks."
I do have to say that their support team responded to my ticket in a matter of minutes, which was nice to see, I was renting 8THs for 900 hours coming from an R4. Maybe I did make a mistake, but I was using a saved profile that worked in the past. The one thing I really don't like about this whole deal is that if you look at the renter's current rental history, I'm listed as green (positive).