Welcome to the board Spades, you’ve picked the perfect place to lose your V card. I did the same thing a couple days before my 30th and it was one of the best things I’ve ever done.
On to your questions: I’m pretty sure you can check in anytime as the Ranch is open 24/7. You can most definitely enter the bar before partying with a lady and I highly encourage you to, it doesn’t commit you to partying or spending anything. It is merely a great environment to visit with and get to know the ladies. I believe you can split up the payments, but you should be able to confirm that with the office when you check in. Have a great time, you won’t regret it!