1. Not at all.
2. Nope. In my opinion, not in the slightest.
3. No problem. And you don't have to find a ball to declare it unplayable. Unless it is in a water hazard you can declare a ball unplayable at any time. Under the rules you can declare a ball sitting one inch from the hole unplayable.
4. The ball isn't lost when you abandon the search. The ball is lost when...
a. It is not found or identified as his by the player within five minutes after the player's side or his or their caddies have begun to search for it; or
b. The player has made a stroke at a provisional ball from the place where the original ball is likely to be or from a point nearer the hole than that place (see Rule 27-2b); or
c. The player has put another ball into play under penalty of stroke and distance (see Rule 27-1a); or
d. The player has put another ball into play because it is known or virtually certain that the ball, which has not been found, has been moved by an outside agency (see Rule 18-1), is in an obstruction (see Rule 24-3), is in an abnormal ground condition (see Rule 25-1c) or is in a water hazard (see Rule 26-1); or
e. The player has made a stroke at a substituted ball.
I know conventional wisdom says you should always help someone look for their ball. I often don't want help. Drives me nuts when I have a provisional in a perfect spot and I want to do as you've suggested and look for the first ball but only in places I wouldn't mind being and then some do-gooder finds my ball stuck in an unplayable lie or hazard.
I think you're fine with everything you presented JD. It's pretty much standard ops in our matches.