Building a dropdown from a worksheet

[Phillips]

I would like to build up a dropdown with the records that meet a certain
condition.

I would like this to be done every 15 min or so. I would also like to know
if this list is different than the one created the last time. (basically,
this is for appointments)

Would this slow down the userform? Would I "lose my spot" if the userform is
already on a record?
I would then like to be able to select one of the records and go to it it I
choose to.

How would I do this?

Thanks
Phil