Valid theoretical question (I think it will error with overflow), but do you practically think you'll get there? bigint can go up to 9,223,372,036,854,775,807

That's pretty big... Just to try and...

yup, either way is probably fine -- whichever way works.. I can't see any benefits of doing it one way or the other

check out php's array_values function, which will essentially reindex the arrays

If you wanted to use php functions to do the validation (say against database entries and such), then you might want to consider using an ajax library such as xajax, and make it look spiffy using...