Re: length....you need to know your storage limitations
Personally I use 8 feet..let's me make up to seven ft leaders...you can use many different types of boards ...I started with a 1 x3 ...8ft...piece I happened to have...I'll give you what I think is better later...some folks make their boards in 4 ft sections and join them for various lengths.
Re: peg positons...You can use Kathy's and just adjust according to %...lots use 40% 30% 30%....however I would suggest you use Parnelli's "Big Furled Leaders Formula"...do a search on FAOL....its been discussed...
This is what I would suggest you do...just my opinion...others will differ....as you said lots out there.
I would make my board...[see below]....and make some leaders based on Kathy's technique....then you can see if you want to move on...
Consider twisting both legs at the same time...
Consider going motorized
Consider using a swivel setup at the tippet end ...so you don't have to hang your board...everything done horizontal
Re; what to use...if you are nymphing use fluorocarbon...for dries most folks use uni thread.....personally I would start with Coats and Clark Embroidery thread till I was comfortable with my skill...less expensive but works fine.
Now for the board ...I submit to you that the following board is as inexpensive ...quick to do...and versatile as any ...the pegs require a little ....
Go to Lowes or Home Depot and get a 4 x4 plain pegboard....you could get 4 x8 pegboard but it is more money and a little harder to handle....
Have the store cut the pegboard into strips of equally spaced 5 rows of holes....you will be adjoining these 4 ft lengths...I mounted them on an 8ft 1X3 fir strip...you can always add another 4 ft extension if you want.
Hope these pictures help...
In the first picture it's the middle one I'm taking about ...the one on the right uses slots..