Hi,
Here's my view on the %'s:
1. Site had some issues and was down for 3-4 hours. 0.25% - Google discounts downtime if it's occasional
2. To reduce the load site was blocked for all IP's other than our country for three days - It depends how much traffic is from other countries. If all your traffic was from other countries, then it would be 10%. If it's half your traffic from other countries, 5%, etc..
3. Google sent us an alert - Googlebot found an extremely high number of URLs on your site. (Most of these pages are no indexed or have a canonical) 0 - 5% - This doesn't sound like a particularly serious alert
4. Banner advertisements on publisher websites that linked to our site via affiliate URL reduced by 60% Again you need to monitor what % of your traffic comes from these affiliate sites. If 20% of your traffic is from these affiliate schemes, then this would account for a 12% drop in traffic.
The MyBlogGuest network got penalised at the start of May, if you have any articles out there that you placed via MyBlogGuest, that's a potential problem. Also you need to delete any links that are automated.There are a lot of factors that effect SEO, it could be a competitor has overtaken you for some of your main keywords, in which case you need to do some more high quality link building. Is your content up-to-date, etc?Hope that helps!