1. Fishing line, or better yet -- floss. It's softer. The badges will be reusable if you get that 3M tape stuff and razorblade it to fit perfectly.
2. Possible, but doubtful.
3. Yes, H is held on with two holes. To debadge it and make it look good you have to get the holes filled and the trunk repainted. That's all you can do. Leave the H.
There is a great debadging guide on
www.05dc5.com it's for RSX but the same principal applies for your emblems