Just reread and saw the first question -
If you have to play with the 5, you have a stiff in any case and need to look at dealer bust probabilities.
1. Stand - letting the dealer have the 5 for a total of 10 and a ~ 23% chance of winning (dealer bust probability)
2. Hit - take the 5 leaving the dealer with a 5 and a ~ 42% chance of winning.
3. Double - same as (2) your chances of winning are under 50%, so you should not double
4. Surrender - if you hit (2), your chances of winning are more than 25% so you should not surrender.
So the right answer is.... Hit.
Then smile at the dealer (who just saved you form a double) and ask her to always wait for you. and to only give you 10s on a double.
Also make sure you remember all your dealer bust %ages at the table
That's my take on it...
D