Lots of questions!

Lindsey • 🌈🎀 💙| expecting number 3!
What is your favorite brand of prenatal vitamins? I am starting to take them to help with TTC. 
Is it bad to have sex every day? Does it lower chances of pregnancy? Why does everyone say to have sex every other day and things of that sort?
Are there any other recommended vitamins?
My husband is stationed away from home but comes home in a month for good! We had trouble TTC before he left so I'm hoping we have better luck this time. 
Any input is welcome (: