Thank you for your post.
1.) I do not think that you need to worry about that. Condoms are generally good quality and they are for the sex worker's protection, as much as four yours. Condoms are safe, provided they remain in place and intact.
2.) You would have noticed if the condom had come off or had ripped. Therefore I am confident that the condom remained in place and intact.
3.) Yes, if the semen remained inside of the condom, that is a good sign that it was safe.
4.) Yes, they are safe.
No risk of STDs, and certainly no risk of HIV, if you are confident that the condom remained intact and in place, regardless of the condition of your urethra. If you are in doubt, you could always get a general STD screening, for your reassurance and peace of mind.
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