Look into analytic accounting on financial tab. You probably need to configure them first under Settings. Analytic accounts are used to group transactions and with the right configuration can be selected on both the purchase as well as the sale orders. You can even set budgets and the sorts.

Hi Peter,

You will find the reconciliation function under accounting/periodic processing/reconciliation. This allow to reconciliate all accounts whenever you want and also to decide what to do with the difference.

Good Luck!

The only way I can think of to generate seperate account within the general ledger per supplier, but this seems quite some effort and I don't know if this might cause any side effects in terms of reporting then. 

Creating individual supplier accounts in the chart of account (not the general ledger) is a basic practice for accountant; I am not aware of a module that creates it automatically whenever you create a new partner. Any way there is no side effects to expect; on the contrary this should ease the lisibility of your accounting reports.