I'm trying to estimate CVA of one of my derivatives by valuing a credit default swap (CDS) of my counterparty. However, I don't know how to set up the CDS deal (notional amount, maturity, etc.).
Well, you should use the spread as the default probability.
For example, A CDS spread of 593 bp for five-year Brazilian debt means that default insurance for a notion al amount of USD 1 m costs USD 59,300 p.a.
Consider a 1-year CDS contract and assume that the total premium is paid up front. Let S: CDS spread (premium), p: default probability, R: recovery rate. The protection buyer expects to pay: S. His expected pay-off is (1-R)p. When two parties enter a CDS trade, S is set so that the value of the swap transaction is zero, i.e. S=(1-R)p ↔ S/(1-R)=p.
If R=25%, a spread of 500 bptranslates into p =6.6%. If R=0, we have S=p=5%.
I found this wikipedia article very enlightening. Price and Valuation