Hey there @Boston_Bry - great questions, and thanks for your topic! Firstly, check out our New User Guide - it’ll def prove helpful as you get used to the platform! You might also benefit from our Company Admin Guide, so check that out, too! These guides will answer a lot of your questions. =) 

Now, to your questions, here! 

1. At this time there is no way to set up a single event type with multiple duration options, but I have a workaround for you! Set up one event type and name it something like, “Meeting Room: 30 Minutes,” and then clone it (screenshot of how to do this, below) as many times as you need durations. Then, name the cloned event types, “Meeting Room: 60 Minutes,” and “Meeting Room: 90 minutes” and so on - or whatever iteration of these examples that you’d like! This is the only way to offer multiple duration options at this time, but it works well for many of our users that have asked the same questions you have! 
2. There is no way for an invitee to book multiple time slots in one go. They would need to revisit the booking page to book additional time slots.
3. What you are asking for is a manual confirmation. Unfortunately, Calendly does not currently support manual confirmations. We’ve found that manual confirmation increases the steps you have to take to book meetings. Not having to confirm, deny or reschedule a booking eliminates the email back-and-forth of scheduling. However, you can reschedule or cancel events from your Scheduled Events tab as necessary! To help you maintain control, we’ve also provided lots availability setting options so you don’t have to worry about confirming. When you set your desired availability, the only options invitees have are the time slots that you’re truly prepared for. Here’s some more information about this: Schedules and defining your availability. For greater control over who can schedule with you, you might also consider using secret event types or single-use links!

I hope this helps!