Before answering your questions, may I ask if from what country are you, if you dont mind? Here in the Philippines one of the most recognized website to buy and sell bitcoin is Coins.ph you can use it either in web or in an android/ios phones like a normal bitcoin wallet like Coinbase send/receive and if you dont know yet another one option is Abra.com you can cashin at 7/11 stores nationwide much little cheaper than Coinsph, if your questions are all answered you may lock this thread for now.