On point 2, I'd like to offer a different view, matching my own experiences and those of people I know in other companies who give the same counsel. Once you've made it clear that you were about to leave and you stayed because they offered more money or some other such better deal, they will always, always, be wondering when you're going to actually leave, and that will affect how they plan your participation. It will change things. It's not that you won't be trusted, so much as you will have a track record of leaving. Unless the counter-offer really is spectacular, once you've decided to go, go.