Hi Gary,

First tip, sending the message containing the neck angle question to the whole group, leaves no way to respond directly to the question. Its just a quirk of the forum software. Posting a message to the board  instead is more useful. 

As to the neck angle, I started by creating scale drawings, but found that in most of my examples, about 3 degrees of neck set allowed a bridge in the 5/8 tall range, which worked out fairly well for me. Again, have to recommend drawing it out. (for simplification consider that 3 degrees works out simply to 3mm in 100mm).

As to how to make it work at the box, there is certainly a number of ways to do it. For me the angle cut into the box area of the neck, combined with box top clearance relief works out pretty well. 

Review this build for some more tips. If you look closely at some of the pics, you can see the provision for some neck set:

http://www.cigarboxnation.com/group/intermediatebuildingtipsandtricksforum/forum/topics/build-blog-a-slightly

Angling the neck slightly back really helps a lot...Ive done it on my banjoleles using packing under the neck where it sits on the body to get a better set up...banjoleles have a through rod to the base so you can slacken off and tighten...on my cigar box I made a small wedge on the though neck by the base...the neck is glued to the top of the box...tho my box is upside down so the back opens freely as thats the lid....with me???

Try out the bridge in place and with a long straight edge balanced on the bridge and going up to the nut..you will see the path the strings will take...make your decision from this...i think there are recommended distances strings should be from the fret board at the nut end and at the 12th

Its fiddly and you need a temporary build to find out what angle you will need