Is [broken link removed] of any use? You don't need to include receipts for costs claimed but you should retain them just in case. If the calculations are in any way complicated then it may be a good idea to include your workings (on a separate page if necessary) so that Revenue can see how you arrived at your liability and check that it's correct.
One further question when submitting a CGT return should I also enclose a cheque based on my calculation of tax payable or wait for a response from the Revenue based on their calculation of what I owe?
Revenue will not bill you - you must unilaterally pay up by the relevant due date mentioned in the link above. Note that assessment and payment due dates may not be the same but there's no harm (other than the opportunity cost) in doing both at the same time.
Usual rules re wasting chattel - less than 50 years or capital allowances claim. Suggest you look on revenue website and do search on FOI section but would be surprised if a ruling is available.