Computer Set up - Polars, Bugs, Ballast ?

Just wondering if anyone has insight to computer set up as far as these questions:

1) Glider polars come from new gliders with experienced factory pilot, right. If a glider weighs more now (20-30yrs) since the polar was created does one create a new polar or use the polar in the computer and add ballast in the settings? The added weight could be from more electronics, AD's, or repairs. Would adding more weight to the pilot be correct, however that may take the weight over recommended and don't know how that may effect computer.

2) Does crazing effect wing efficiency like bugs do? Does one guess in air how much bugs percentage is on the wings and set that in the computer?

3) What about a pilot that flys a little sloppy and yaws a little? Would it be beneficial to add a little bug percentage? Or the addition of wing skids?

I know that some of these percentages are minuscule and only the top pilots would know a difference in any bugs, but I would think an average pilot could tell a difference in a significant amount of weight, but not sure how much the computer information would change for glide.

Casey