No by that time the sperms have died. They can only live 3 days/72 hours in the woman's body.
Yes it is possible.
1/2 chance.
Possible multiple and if none seen on ultrasound you could possibly have vanishing twin syndrome.
Yes you can get pregnant if you have vaginal sex and have not taken birth control for 1 month.
No month
Yes that is possible for some. It differs when women start to ovulate after but it can be at 1 month after. There is really no reason why you should not be able to get pregnant by now unless you breastfeed continuously for 6 months and don't give the baby anything else. That might protect you.
Leave her alone
A plasenta is a uterus!
your most likely pregnant
5 weeks is roughly 1 month. You can do the math.
1 month and 2 days.
no