Payslip amount on balance sheet in employee clearing account & equity-retained earnings

First, if you had this edgebander when you started using Manager, you probably should have set it up as a fixed asset. See:

That Guide includes some discussion about loans, as well.

Interest paid on the loan is an expense. Principal payments are posted to the loan liability account. Both the principal and the interest portions of the loan payments are handled from Spend money in a cash account as separate line items. They are equivalent to debits, offsetting the credit against the cash account.

Depreciation on the fixed asset is also an expense. See this Guide:

The procedure is equivalent to debiting depreciation expense and crediting Fixed assets - depreciation (a contra asset account).