Our situation was a bit different but hopefully I can offer suggestions based on our situation. Local building code required steps onto the lawn from the house for an occupancy permit. They're concrete and we built over them with what you see in the link. Our specific concerns were safety while transporting items in/out of the house. And we had an elderly relative for whom stairs were dangerous. So, we built an Egress Porch (really a small deck) over the existing steps, level with the threshold. This provides secure footing while opening the door. Then we choose landing style steps for easily providing assistance to someone in need. If you were to consider a small deck it would provide the security at your door like I mentioned, leave the weep holes open and could still become the 1st step. Other steps could be pavers on concrete to match the patio. Hopefully your patio could be enlarged a few square feet to recover the space necessary for the steps. Hope this helps. Here is a link that might be useful: Our Egress Porch

Paint on concrete doesn't look good or hold up well. You might check into concrete stains if you want to change the color. I haven't seen the stain used on pavers, but it might be possible. There is a masonry adhesive that comes in a tube that we used to anchor flagstones to a concrete-block support structure -- similar to what you have. It was not available at HD, but our local stone supplier had it. It is applied with a caulking gun, is extremely strong, and will hold up to freezing. The stone yard told us the stone would give up before the adhesive would. Definitely go with the polymeric sand. We've been very happy with how it hold up and keeps weeds out.

I think the mix of sandstone and wall is fine. Not sure how I feel about a brown border as that brown feels more red. I would think a tan border would pull it together.

Try it. Next time you kill something green try 1 gallon white vinegar, 2 cups Epsom salts and 1/4 cup liquid Dawn dishwashing soap. Killed poison ivy and growth between pavers for me. It may take repeated applications on invasive/pervasive stuff like poison ivy.