I've got a late '80's model flight computer with an
integrated non-GPS final glide calculator and an IGC GPS
logger. I'm thinking about upgrade options to minimize the
mental workload for these items that I currently have
trouble with:

What's the current wind speed and direction?

What altitude do I need to final glide upwind to airport X
and turn back downwind to home at airport Y?

What airport is easiest to get to when I'm low given
different airport field elevations and current wind
direction.

When should I turn to get home 3 hours after I started this
task?

I'm not really sure what options I have. More generally,
I'm wondering what the PDA's can do. I presume they have no
airspeed/pitot input, no TE input and only GPS altitude.
Is that correct? Can they perform vario/TE/STF/final glide
functions?

I realize they can do GPS moving map, flight track
recording. I suspect they can figure wind from a circling
algorithm, but without TE or airspeed can they replace my
old flight computer? If not, can they supplement it (with
my GPS/pressure logger) so I can avoid the expense of a new
flight computer?

Anyone want to give me some comments here? Thanks.