Hi BigJohnTheBrikkie
1. I am unable to provide the percentage of repayments selected for security checks.
2. Once selected the timescale for the checks to be completed can take up to 6 weeks, but, it can take longer due to the high volume of repayment requests or if addditional information is needed.
I apologise for the delay if you have not yet received your repayment.
3. Yes there will be repayments that were selected that have been issued.
To review your repayment you can contact HMRC by phone/webchat at
Self Assessment: general enquiries
Thank you