"Second, there are numerous passages that speak of him having to remain in heaven until his still-future coming, yet the Holy Spirit is here now. Is that not a "distinction"? "

Not when Jesus said I will never leave you or forsake you.  Not when we are the Body of Christ, not the Body of the Holy Spirit.

Gal 2:16 Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.

Jas 2:24
Ye see then how that by works a man is justified, and not by faith only.