Okay, so......
So King Mickey is originally from Timeless River along with Pete
Correct, key word: Originally, as in that is where they start
so did Pete and Mickey somehow move to the Country of the Musketeers world from Timeless River
Yeah (assuming that they are different worlds anyways)
and then when Mickey left Country of the Musketeer did he go back to Timeless River to live in the new Disney Castle.
Not sure what's being asked here...
If they are different worlds (again, I'm not sure that they're different worlds) the Country of the Musketeers is a different world, then he would have gone back to the Timeless River- which was renamed Disney Castle (after the Castle was built anyway)...
While it's possible he didn't go straight there, he had to go back at some point (he is king after all)
Is Minnie originally from the Country of the Musketeers along with Donald and Goofy?
I... don't know. Use your best judgement from what you've seen here. I don't know of any proof for either possibility there.
And then Mickey went to Symphony of Sorcery to train with Yen Sid?
At some point, yes
And why is Yen Sids tower a stand alone world in Birth By Sleep before the worlds were destroyed even though it should be with the rest of Symphony of Sorcery, did he like seperate his tower earlier from the rest of the world before it fell into darkness?
That's an interesting thought... Certainly possible, something could have happened to it as well
And why was Disney Castle being constructed during KH2 even though Mickey wasn't king?
Are you referring to it being constructed in Timeless River? I suppose that's because the people wanted to protect their treasure... Mickey was probably later nominated the one to protect it- thus King... idk
And how was Mickey able to travel to Country of the Musketeers anyway?
Well, Master Xehanort said in his reports that
A portion of Xehanort's Report V said:
At present, the lanes and corridors that run between the worlds may only be traversed by us Keyblade wielders, and those who have given themselves over to darkness.
As the former, our duty is to cross the chasms between worlds and guard against the latter, whose darkness corrupts and contaminates, so that no world need ever be lost again.
Now, much time has passed since then and gummy travel is also available... SO! Either he used the keyblade, ran across a corridor of darkness, or had some sort gummy travel
And why was Pete forgiven for what he did when he was the captain of the musketeers by trying to kill everyone and wasn't forgiven in BBS when all he did was get mad about not winning a contest, it just doesn't make sense.
His chances were all up, that was Strike III so-to-speak
I'm just asking because the addition of Symphony of Sorecery and Country of the Musketeer seem to have created a few plot holes in the timeline of King Mickey and all of the other Disney Castle characters.
... and you ask a bunch of questions x_X
hopefully that helped a bit though ^_^