Welcome to the STD forum. Happy holidays.
You have no worries. STDs are not transmitted by fingering. There are theoretical risks for HPV and perhaps herpes, but even those are too low to worry about. In the 30+ years I have been seeing patients in a busy STD clinic, I have never seen someone with an STD whose only exposuer was hand-genital contact.
Second, your symptoms do not suggest any STD. They are not due to any medical condition you caught during the sexual exposure from last May (or any other sexual event).
To the specific questions:
1) No STD risk here.
2) It would have been obvious if the condom were broken. It's not something you can miss.
3 and 4) Your symptoms are not due to an STD and you do not need testing for STDs. If you remain concerned about them, see a health care provider. But forget STDs as a cause.
Here are two threads that explain why non-intercourse sex carries little or no STD risk:
http://www.medhelp.org/posts/show/922472
http://www.medhelp.org/posts/show/1119533 (In this one, read my closing comment at the end).
Regards-- HHH, MD