You can either walk or take the boat from the S/D to DHS. The walk takes under 20 mins, depending on pace...I do it in 15. The boat takes about 10 mins..not including any wait times. To walk it...just leave the Dolphin, go up and over the bridge that is just past the boat dock. At the BW entrance, go right and you will see a sidewalk with signage to DHS..it runs behind BW and along the canal. Very pleasant walk.
You could rent a cab from Pop to the Dolphin...should be under $15, I paid $10 (including tip) from YC to Pop a few years ago.
As far as what type vehicle will be there...if you rented a van, or similar vehicle, then it should be there. I have actually rented a sedan and when I got to the counter at the Dolphin, have been offered a minivan for the same price since no one wanted one!!!
while this site gives you an 'idea' of how to get from point A to point B, it isn't always correct. Some of us go to that site every so often to check it out. It doesn't always give the best route..or sometimes it just gives plain old wrong info. That's why you won't see many of us recommending it.