I'm going to take a stab at answering your question, even though it's complex and I'm not looking at all the details.
1) You can submit your overall foreign tax liability balanced against profits and losses for all foreign investments. Usually this means that you will be able to claim most or all of your foreign taxes even when you need to file 1116, but not always.
2) No, you do not need to claim a credit for foreign taxes paid just because you can--but you shouldn't pick and choose, as that could get dicey as far as your intent if the IRS reviewed it.
3) You don't need to do it account by account, just collect and summarize the information from all the accounts on Form 1116, etc. Taxes are paid by taxpayer, not by account. All accounts you report should have your tax ID number on the forms you receive, or if a joint return one of both of you.
