I don't think there's a reasonable place to stop the Builder between St. Paul and St. Cloud right now. Coon Rapids Foley Boulevard would make sense if it were ever built, as would Northeast Minneapolis (even less likely to be built). Fridley might make sense but the platform would probably have to be lengthened. BNSF doesn't want the EB blocking its mainline in that area while making multiple stops on a short platform.
Regarding the St. Cloud station location, my instinct is for something on 3rd St. SE, with great expressway access *and* walking distance of downtown. This would require buying some buildings, though.
US 10 already has good access with the current location, so you're basically gaining the walking distance to downtown benefit. This might just be better served by a bus; if anything, finding a way to get it closer to SCSU would be better, though I don't think that's possible.
I'm looking more at access from the west on 94, but to do that you have to go off the mainline and onto feeder tracks that probably aren't kept up to spec. Anyone coming from western Stearns County (or west of St. Cloud in general) would not want to drive through St. Cloud just to catch the train to Minneapolis. They'll either go to a station much easier to access from 94 (say, Becker or Big Lake) or just drive down.
As for Foley Blvd., even if the station is built there parking will be an issue. That parking lot fills up on weekdays with commuters, and I highly doubt Metro Transit wants 60-100 Amtrak patrons taking up spots there. Fridley makes more sense from that standpoint, as there's plenty of excess parking capacity there. Whether BNSF will take it or not is another story. Any other stations "gut check" in my mind to be too far north to be of benefit to most people in the Cities, though it's not really that much worse.
Nothing that I've heard. I think it would be a good idea, though the Builder's eastbound schedule would have a stop during rush hour for the Northstar, which would be problematic for commuters.
Happily (cough, cough) this would not appear to be a conflict on most days.
Amtrak train status history - Check on time performance and Amtrak delays Status for train 8 arriving into SCD2013-11-25: Scheduled: 5:14 am Actual: 10:56 am Delay: 348 minutes
2013-11-24: Scheduled: 5:14 am Actual: 8:15 am Delay: 187 minutes
2013-11-23: Scheduled: 5:14 am Actual: 7:59 am Delay: 169 minutes
2013-11-22: Scheduled: 5:14 am Actual: 12:17 pm Delay: 429 minutes
2013-11-21: Scheduled: 5:14 am Actual: 7:35 am Delay: 145 minutes
2013-11-09: Scheduled: 5:14 am Actual: 7:11 am Delay: 132 minutes
2013-11-08: Scheduled: 5:14 am Actual: 9:02 am Delay: 233 minutes
2013-11-07: Scheduled: 5:14 am Actual: 9:18 am Delay: 249 minutes
2013-11-06: Scheduled: 5:14 am Actual: 9:33 am Delay: 263 minutes
2013-10-29: Scheduled: 5:14 am Actual: 9:19 am Delay: 250 minutes
Average delay is 240 minutes
If only Amtrak could allow it through based on the fact they're running so late.
Hopefully within the next couple years, though, Amtrak should be running relatively on-time. When that happens, they'll be clashing with the Northstars coming in. Assuming an hour between SCD and Fridley, you're looking at 6:14am in Fridley, which hits just before the 6:24am Northstar. There's also a 6:54, 7:24, and 7:54am Northstar they'd contend with, so even if they're running an hour late they'd have to go in between them, and I'm not sure where BNSF would hold the Builder at to let a Northstar pass.
While I think it makes sense to have a Fridley stop, it seems easier to find a way for Amtrak to validate parking at SPUD, and might even be cheaper overall. For now, I think Amtrak expects passengers who want free parking to use SCD or RDW.