The starting point is pretty much Paia, although the CD starts a bit before that. It isn't about Hana- there really isn't that much to Hana itself- it is about everything along the road. We went past Hana to the to the Seven Sacred Pools which is in the Haleakala National Park. It is the point past there which makes the full circle that many insurance companies warn against. The road is fine all the way to Hana. As far as the road to Hana itself- I've been on roads in Colorado and Arkansas in the mainland U.S. that were a lot scarier. Aside from the fact the road is narrow in parts, and there are some spots where you and oncoming traffic have to take turns-the road itself is fine. You don't have to go the whole way, you can turn around- you just might have to drive a little ways to find a spot to turn around. There are lots of people that get so caught up in spots along the way and stay in a certain spot so long that they turn around before they get to Hana to get back before dark. It is only 45 miles between Paia and Hana, and the drive itself if you didn't stop would only be about an hour and 45 minutes. I think on the way back we even made it in a little less than that as there was not much traffic at all on our way back. We did not make it back before dark- we drove about half the way in the dark which meant there was pretty much no oncoming traffic at all, except for a few probably locals and not much on our side either.
It is about 30 miles from the Hyatt/Westin area to Paia. I think it took us about 40 to 45 minutes.
As far as the beach by the Hyatt, right in front of the hotel it is not a very deep strand of beach, but if you just take your stuff and walk a very short way either direction, there is plenty of nice beach to relax on. If you walk the direction away from the other resorts there is an area where a lot of people park and come to the beach in that area and there are often turtles (or so we were told), we saw a couple turtles so I would guess the employee that told us was right. If you walk towards the other resorts-there is a lot of beach that way and down towards the end of that strip was where we found the place with the calmest water (the time we were there the water was rough due to a tropical storm approaching).
I was overwhelmed before we went to Hawaii too. Don't stress, once you get there it is not hard at all. Once thing about Maui is that there is pretty much only one road to get to anywhere you want to go. It is not hard to get around at all-- unless there is an accident or major traffic or other issue on that one road!
The things that we missed that I was most sorry about was 1. I wished we had more time to explore Paia because it looked interesting. Because we got too late a start on the Road to Hana, we did not get back to Paia until late. We had dinner there, but the shops were closed. I wish I had forced DD and DH to get moving earlier, maybe even skipped the free breakfast at the Hyatt and gotten an earlier start. 2. We missed seeing the Banyan tree in Lahaina- I had seen in on a show on tv, but didn't even realize that was where it was and that we were right there until we were back from our trip. We were exploring Lahaina in the evening and hitting all the shops there, but just didn't walk down far enough-plus it was dark. Those are the couple of things that it would have been pretty easy for us to do as we were right in the areas, but we missed.