Congratulations, hope you end up enjoying your Astro as much as I have enjoyed all of mine.
1) I've never had ABS issues, well none that weren't caused by bad wheel bearings. Pretty sure Auto Zone can read the ABS codes for you for free.
2) Grab the idler arm and try moving it up and down. They shouldn't move too much. There are lots of grease zerks on the front end. I push fresh grease every oil change. Upper and lower ball joints, inner and outer tie rods, idler arms, pitman arm.
3) I'm using Ranchos on Grumpy and Gabriels on Green, pretty happy with both.