A quick TL: DR for those who don't ahve time to read the full report
https://dailyhive.com/vancouver/north-shore-rapid-transit-study-skytrain
The plan and profile pics present a better look at the engineering challenge involved.
Option 5C to use existing Ironworkers bridge was eliminated because the bridge is too old to support new structure.
Option 2A and 3A has 2 problems: both assume it'll be a branch line from Expo so train frequency will be affected. The tunnel has a 6% gradient approaching the North Shore. Yes, LIM powered trains can tackle it but it may increase wear and tear on the trains. Also, good luck dealing with the ice buildups when it snows.
Options 1A: This one should've been deemed infeasible as well but I guess they are doing it for PR's sakes. Build a tunnel across the longest and deepest part of the inlet? no thanks. There are 2 sub-options: build new separate line, or rebuild 1.1km of Canada Line and lower Waterfront and VanCityCenter by about 25m. Clearly 1A makes the least sense.
Option 5B2: extend existing Expo line from Waterfront along hastings, via a new bridge next to Iron Workers, and then loop back to Londsdale.
Option 5B: new line from Brentwood and via new bridge next to Iron Workers and end at Lonsdale.
If I had to choose, I'd go with 5B. I prefer having a north/south line running from Lonsdale to Brentwood (with possible extension to Metrotown) than an indirect detour running on Hastings. Option 5B2 will not provide time savings compared to Seabus (in fact, it'll probably take longer). If Expo were to be extended along Hastings, I think it's better to have it terminate at Kootney Loop, which will act as a transfer station with the north/south line.
Tbh, I think the study will say all options will be extremely expensive and the money is better spent getting more seabuses.