payment method, account determination with no house bank GL

Dear Expert:

I'm designing my client's bank determination, I have two solution :(1) in house bank, we don't maintain GL account, but in bank determination/bank account, we define GL in bank sub-account, (2), in house bank, we maintain GL

which solution is better? why?

I have payment method E, C, G,T for company code 0020, in ranking order, if I define "G USD 1 HSBC" and " C 1 CITI", does it mean when we do vendor payment in USD, payment method G, HSBC account will be deducted? if I leave currency blank, does every currency payment for C will go to citi?

since I didn't specify T in ranking order, which bank account will be deducted for vendor payment method T? what's the purpose of ranking order?