First time taking a Pill

Aj
Hi guys, this is my first time ever using a contraception. I was raised somewhere that sex related thing is pretty taboo. But nonetheless I need to ask about these if you have any experiences with this stuff already..
I'm currently abroad and have a partner. We decide to get a contraception because he told me it is safer that way. So I go to a doctor with him to consult about this and I choosed the pill, since I am not keen of other methods (I want to get married in 1-2 years so I thought maybe just the pill?) 
But I forgot to ask a couple of these things to the doctor because we only have 10mins to talk since my insurance do not cover the cost for it 😪
1. This is my first period day and I took it. When is it safe to have sex after taking the 1st pil on the first strip? 
2. Soooo.. basically is it safe to finish inside me? As long as I take the pill everyday regularly? I never experienced it...
3. About weight gain.... as long as we exercise, eating right and aware that the hormonal change is the one causing the craving so still maintain a normal eating habit, is it okay right?
Thank you in advanceddd.