2 quickies

First question is a yes. The second, well there are a lot of folks here that use a 100:1 ratio, with a good oil. Lots of folks use other ratios as well. It just depends on you and how you feel about it.

Search for oil fuel ratio in the search box and you'll find a lot to read.

#41 chain is a direct replacement.
Do you mean 4 heat cycles for a break in?
If so, for proper break in you need to run at least 2 tank fulls, about 1 gallon at 24:1 gas to oil ratio. After that run a 32:1 ratio for another 2 tank fulls. As soon as you clock 500 miles it is pretty much broken in. Do not baby it during break in, but also do not ride it like you stole it either. Ride it normal with a few short full throttle bursts for no longer than 15 seconds or so. You need to put a strong load on the engine in short, time spaced, intervals in order to properly break in the piston rings. The best time for this to occur is in the first 25 miles or so as the sharp edges of the cross hatch finish in the cylinder will get worn smooth with time. A smooth cylinder will take much longer to break in the piston rings.

As for the rich coloring on the spark plug, that will change as the engine breaks in.
A rich mixture is good during break in anyways. Unless you are experiencing flooding problems with the carburetor, leave well enough alone until the break in is completed, then fine tune it for best performance.

Edit after reading the other posts that were posted while I was typing:

The stock jetting is usually slightly too rich from the factory.