1. Just connect the ride up in the editor and then ride it in the editor, thats what I do to test, well, actually, thats ALL I can do to test
most people on the site know why hehehe. But anyway, I think thats the best idea, I don't think you have to open up the simulator every time you want to test a section, just make the section, then connect the ride up, then ride it in the sim, then make any changes needed, then disconnect it and build the next section [;)] then repeat lol.
2. 280ft is very tall for a B&M twister, I would set a limit of 200ft myself. I guess its your design though and if you can make it realistic then you can make it as high as you want, but in real life 280ft for a B&M twister ........ just can't see it happening.
3. Well, Rita at Alton Towers has a 4.7g helix on it, I've ridden it and it didn't feel all that much, so I guess 4.7 g is fine, I try to set a limit of 5 g's and any coaster of mine, but I like to keep the g's at around 4.5g's at their highest, if you can keep it so that the highest g's on your ride are 4.5 positive g's, then you should get good marks in that section of the rating. Make sure the other g's are realistic though, like the lats should really stick below 1g or above -1g, although its not so bad if you go to about 1.2g or -1.2g, I can't see many people knocking off points for that. Negatives g's should be about the same as lats, try not to go too far below -1g with the negatives, I guess -1.5 is about the limit for negative g's though.
Hope I've helped [:)]