I have an answer to the most important of those questions... yes, you can avoid having a near-heart-stopping episode every time a new opportunity crosses your desk. And it's not that far to go from wrecked to relaxed. You just have to know what you're doing.
Oh, is that all? Actually, yes. Know what it would take to leave the comfort of your current desk and chair, your current happy hour buddies, your current paycheck, your current perks, your current Keurig. Think about this financially, location-wise, emotionally and any other ways it matters to you. Do you want more authority? More autonomy? A shorter commute? Less travel? More travel? A better boss? A wireless mouse?
When you get to your new job, what will you be writing home about? What will you be bragging about to all your friends? What will your family be happy about? Whatever that is, it's your talisman for the job search. Stay focused on what you want.
And know, too, what you bring to the table. What's your sweet spot? Which of your talents are being squandered? Where can you really add value in a new role?
Once you know why you're moving, and why another organization would want you, then you're on your way. If the new opportunity fits, you have nothing to be nervous about. And if it doesn't, you have nothing to pursue. And if you need a hand working that out, let me know. I can probably help you out.