2 accounts

I have an existing personal account with an email address that I use from desktop. Would like to add another separate account for trading self directed IRA LLC funds; can I do that from the same email address and computer? If not, could I trade IRA funds from my laptop and different email address?

You can set up as many national currency accounts as you like in Bisq, so long as you use the correct one when making your payments. That is, you must make your payment via the same account specified in the details of each specific trade you make or take. Other than that, there are no restrictions on working with multiple accounts / using the same email across accounts, etc.