this question has been asked before.
here are some of the threads from other forums where there are many good ideas
http://diylightanimation.com/index.php?topic=13323.msg169539#msg169539
i especially like post 3,8 and 11.
http://auschristmaslighting.com/forums/index.php/topic,3711.0.html
http://doityourselfchristmas.com/forums/showthread.php?29040-How-I-Built-my-Pixel-Tree
http://www.diychristmas.org/vb1/showthread.php?1465-Design-and-construction-of-a-Pixel-Mega-Tree
that will give you over 100 posts to read.
in answer to your questions for my megatree
1- how many degrees? I assume 360 would be optimum, but very costly
180 degrees. if i make a 360 degree tree some of the effects bleed through together, like text and pictyres.
360 would look awesome with meteors, bars and trhe others that are not oriented.
2- how many strands? Based on answer to #1 and decent visualization of spacing between them
20 strands of 4m 120 pixels flex strips. tm1809.
3- folded over? Please explain the pro's and cons
effects look best with the most strands you can get. make a 64 strand tree cool, cost not so much. so to save money people fold the strings in half to get more density. the downside is their trees are now half as big.
a good start would be 8 strings of tm1804 , 128 nodes. these are > 30' long. fold in half and you get a 15' megatree with 16 strands.
you can build multiple model sin xlights and try effects out on them to get an idea what tree would like without having to buy the hardware./
4- lights? Strands, strips, type, model#?
strings have the advanyage of making taller trees. you can get 4-5" spacing between each light.
flex strips are way denser. my 120 node 1809 has 1.3" spacing. advantage of flex strips the vertical spacing is perfect.
5- frame? Sean has a great one...how do you do yours? How tall?