1. 2-3k probably is more the norm for parachute opening, It has been a
while since I have dropped any on a regular basis. However I do recall
that for certification the are required to do a drop from low altitude,
It seems to me it somewhere between 3,000 and 3,500 ft agl to be
dropped from.

Anyway the point being the lower I am the more time and easer the
parachute will be to see.

2. I agree you would never be able to see or avoid a free falling
skydiver.

3. Funny my Sectional doesn't show a Parachute symbol, yet the are
skydiving almost Dawn to Dusk 7 days a week. On the other hand they are
very good about making Radio calls for dropping parachutes, and If you
are aware that they are there they are easy to avoid.

Brian