About Tracers/Ammo mix.

The standard RAF loadouts at the start of the BoB. On an 8 x.303 gun aircraft
3 Guns loaded with bog standard .303 ball ammo
2 Guns loaded with Armour piercing
2 Guns loaded with Mk IV Incendiary Tracer (burns on way to target)
1 Gun loaded with Mk VI De Wilde

Or

4 Guns loaded with ball
2 with AP
2 with MK VI, the last 4 rounds were all Mk IV tracer to let the pilot know when the ammo had run out

Unlike the other Air forces of WWII the RAF preferred to load each gun with only one type of ammo.

Something I forgot to ask is if SoW tanks (and grounds objects in general) will have different skins for different battlefield (desert,regular green,snow...)?

Eventually, but right now they're probably all going to be summer 1940 style camouflage (I'm guessing) since there isn't any real need for additional paint schemes. Adding them doesn't take long at all, and you'll probably see that if they do N. Africa or the invasion of Russia.

That kind of makes sense. Different ammo cycles the gun differently. Mixing ammo could cause "short cycles" jamming the gun. And for other reasons, one type of ammo per gun makes sense.

Splitter

I think this has been confirmed by mr. Maddox himself very recently. It's either in the thread about the Igromir expo, or even in this very topic. I don't know if it's a feature we'll see right away on release, but i have a distinct recollection that he did talk about personalizing the ammo belt loadouts being included in the simulator at some point.

Also would it allow you to harmonize the gun so all the different ammo types were converging at the same point?

But they mixed ammo in reality, probably for a good reason.

If I had to bet, I'd say the tracer-only gun will fail first.
(take a guess why)

Due to barrel fouling? Well yes, perhaps the tracer round would cause that - but the armourers would be cleaning and checking all the guns after a day. Excessively pitted barrels would be replaced pretty smartly.

Also, some of the RAF pilots didn't like having the last 4 rounds in the incendiary guns to be tracer because thay noticed that some of the German pilots were waiting till they saw them before they engaged.

I can find no mention of the RAF fighter command using mixed ammo belts till 1942. (I'm talking MG wise, not cannons).

I've no idea what Bomber commands practice was.

In fact the whole gun will be full of this ugly stuff, everywhere. :-x