Hi!
Question 1: Who is the best SE leader for trying out that economy of the vanilla leaders?
My favourite has always been Gandhi (but probably more in his post-Warlords incarnation.)
As has been stated, any combination of Industrious, Spiritual and Philosophical makes for a great SE leader.
IMHO:
- For a peaceful SE, Philosophical + whatever.
- For a warring SE, Spiritual + whatever.
Question 2: Are lumber mills, after being railroaded ect that bad? or is chopping them and replacing them with something else earlier better?
Lumbermills are great as long as you're willing to wait half the game for them (I typically am not).
Whether or not chopping them early is "better" is a call you have to make situationally.
As a general rule (especially in BtS), I chop trees in an SE and leave them in a CE.
(Based on the generalization that SE's are good early-game systems and that CE's are good late-game systems.)
Question 3: When I am running a primarily(little to no cottages) SE should I run 100 science and add some merchants to make up or run 100 cash and have tons of scientists?
I think that's a judgement call you can make based solely on your own preferences.
The thing to remember is that at 100%

, +
gold% buildings like Banks are virtually worthless unless Merchants are being run in the city.
Similarly, +
science% buildings like Universities are virtually worthless when running at 100%

.
BUT: Based on that information, you could deduce that 100%

is better, because most +
science% buildings do nothing more than boost science, while most +
gold% buildings also boost

and

(and are thus necessary anyway -- regardless of the sliders).
Also, how many people actually run the 0% science tactic for cash the 100% science at a loss? How much cash do you want to stockpile before you go back to 0 and does switching work better in the early game, middle or late?
Because of Vanilla rounding errors, you can lose a fairly substantial amount of

and

running your sliders at anything other than 0% or 100%.
However, since all rounding was relegated to the Financial advisor in Warlords, the most you stand to 'save' running "binary research" in non-Vanilla Civ4 is 0.99

, 0.99

& 0.99

(in BtS).