Another general tip on posting, if you direct your questions to specific people then others who may have experience or opinion on the subject may not post, because you did not as for open input. You'll get more discussion, and chance for an answer if you list the questions alone, and reserve the one-on-one for specifics.

About the arms, I've not done it myself, but I've seen it discussed on other forums that tend to pure "old school" approach, like the HAMB, killbillet, or olskoolrodz so I think it's done. You just need to understand the geometry and play within the rules. Also know that you're making a one off, custom part and if you break it or wreck it later you'll be making another one.... If you haven't seen it lots of people go back to a R&C article as a basic reference Basic Suspension Geometry Lessons - Rod And Custom Magazine

On your steering rack, the position of the rack is going to be driven by the location of your steering arms, right? If they're aligned low, off the bottom of the spindle then your rack is going to be on brackets at that level with the chassis at ride height, right? That gives you the necessary travel for suspension movement. Others may jump in here - I'm only speaking from what I've seen. Never used R&P myself. If I've gone too basic in my reply don't take offense, as none is intended.