[TheForge] Swedge block question

[Bob Rackers]

I had an interesting day in the blacksmith shop today, and it sparked a couple
of questions.
I have to forge a 15.5" length of 3/4 round to a 31" long half-round profile
(i.e. imagine cutting the 3/4 round down the center and using one half or the
other).
I thought it would be a simple enough matter to place the rod into the 3/4"
slot of my swedge block and peen across the length of the bar to stretch it
out.
It didn't exactly work as well as I'd have thought. After going the entire
length, the bar only grew in length by 4".
So my questions are:
1. How deep should the 3/4" round slot (on the edge of the swedge block) be if
the width is 3/4"?
I've rounded the edges a bit, though I think a little more wouldn't hurt.
I assume it has to be less than 3/8", but how much less?

2. Is there a rule of thumb I can use for the other slots as well?
I still have to clean up the rough casting on some of them.

3. What is the best (most efficient) way to double the length of the bar and
end up with the half-round profile I need?
Forge it square first, etc.?
No power hammer of any sort (yet), so that option's out.

4. What's the best way to both flatten and straighten this length (or longer)
once I have the profile complete?
As I work it I try to keep it relatively flat, straight and untwisted as I go,
but I need to end up with the flat section on the same plane when I'm done.

5. While I'm asking questions, I might as well ask for the best method of
making two 90 degree bends (sideways) in this bar once I have the length I
need.
This bar is going to be attached underneath a wooden board, with the flat
section against the board.

Thanks.

Bob