Ive gotten really close to finishing the entire war a couple of times but keep getting killed
having your base changed without requesting a transfer is normal. Watch your messages and you 'should' be notified of the the change.
I suppose that in the 'stock' game if you aquire massively ridculous amounts of tonnage you could get retired never seen that though.
Most sub commander carrers dident span the entire war anyhow. At least not in active duty. Hrm... desk job simulator doesent excite me too much :p