Warning: Novel, incoming...
A lot of your questions really depend on what specific date you're wanting to go. For example, my husband and I went to HHN last year for our honeymoon. We bought the Rush Of Fear passes (which I HIGHLY recommend if you're going to be in town during those first 3 weeks). We got to Orlando on Wednesday and did the regular park things during the day followed by HHN on Thursday, Friday and Saturday. This was ideal because having all 3 nights covered on the Rush Of Fear, we didn't have to worry about rushing and were able to experience everything without any stress or any worry of missing anything. We only did 2 to 3 houses per night but that still gave us plenty of time to see all the shows, ride a few rides, enjoy dinner at Finnegan's (where we got engaged exactly one year earlier) and experience all of the sights of the evening. The reassurance of knowing we had 3 nights to cover the park, we weren't so stressed about having to wait a little extra time for one house, because we knew we would get to everything regardless of the wait times. The earlier in the season, the slower the crowds tend to be, but I'm not 100% sure on if opening night still fits that pattern.
The day time is a little harder to give a 100% answer because a lot of it depends on what day of the week. That being said, when we went, Thursday was the slowest day and we probably could have done most everything that would interest us (in both parks) that day, but again, it was our honeymoon so we were relaxing and taking our time. We easily accomplished everything we wanted to in the 3 days we had though. Actually, we did our favorites all 3 days with very little wait for anything. I'm pretty sure the longest waits we had were for soda refills. From what I've always seen, the Halloween time is not a busy time of year other than for the Halloween Horror Nights events.
Hotels, everyone has different preferences. I personally am not a picky person. I've stayed in some really nice hotels ($150+ a night with all the extras) and some really awful hotels ($25 a night with no sheets on the bed). I want a hotel for a bed and a shower. I don't need extra ammenities. I don't need breakfast. I don't need a spa in the hotel. I don't need a mini-bar. I just want a clean bed and a place to shower after the parks. You have beds with no bugs and a shower that works? I'm sold. You have a coffee maker in the room? I'm beyond happy. Given that, Hubby and I have stayed at the EconoLodge on International twice now. Once for Halloween Horror Nights and once during Spring Break. Both times they met our expectations and then some. The staff were all very nice, the rooms were clean and they had everything I needed. They were more than happy to give us a fair share of coffee packets without giving us any flack for asking. They are only a 5 minute drive from the park, close to a ton of restaurants on International Drive, and are around $40 a night. Hard to beat, IMO.
Hope that helped.