The following people contibuted to this article. Fresh super glues with an accelerator. I use the slow set type, but that is my choice. Try 5 Minute epoxy. Superglue of various types.
Auto body fillers for gross filling.
I like auto body filler and Humbrols red filler. Plastic filler as Revells Plasto don't stick. I prefer Floquil grey primer myself. Easily applied, coats well, shows up last minute flaws as well. I've airbrushed on thinned white acrylics too.