Lawn and Garden - your turn to help

My last post about the yard and garden was all confident but really we have a few (well, more than a few) issues left to resolve. I thought I'd list a few of them here and get some suggestions from you.

The first is a sinking walkway to our backyard. Most of these slate sheets have sunken below ground level since we moved in.

You can see from this angle that the grass and dirt has overtaken them. It's not really an inviting walk into our backyard:

We did actually clear this area out next to the side of the house a bit, and plant some snowdrops that our neighbor gave us, so there's that at least:

While walking through our neighborhood, I saw someone with this and WANT (it's not creepy to randomly photograph strangers' yards, right? I mean they're in the neighborhood so that makes it cool, right?). I guess this would be pretty hard to do, given that ours is on a hill and curved. We'd need a lot of pebbles, too.

 Any other ideas on how to improve our walkway?

Second, I'm so happy that we finally got the salvia to grow in our front garden. However, for two years in a row now, the first heavy rain after they come up makes them sink to the ground and stay there. They are in the back against the stoop (because they are tall enough in theory to poke out above the hosta and azalea), but you can't see them here:

You can see from these two photos taken from above that they have basically fallen down flat in a circle out from the center. These kind of plants don't seem like they would easily be staked, since they are in so many parts. Do I just need to embrace the fact that they are flat and move them to a more prominent place in front of the other plants?

Next on the list, our mint. It's got black dots and holes on it. A search for this problem reveals that it is either a fungus or blight that makes me think we have to cut it all back and hope for better next year. But none of the descriptions and pictures look quite like ours:

And finally for today, some aggressive weeds trying to take over our brick patio. The holes between the bricks are obviously no longer well filled with sand or cement or whatever was there to begin with, so there are weeds everywhere. We're not fond of using weed killer anyway but honestly in this case it hasn't even seemed to make a dent. Here it is just before I cleaned it up by hand:

 Here's proof that after a lot of manual labor, it actually looked nice:

 And here's the same spot (with no hammock base) just 3 weeks later again.

Any quick fixes? Roundup had very little impact when we used it last year, so we haven't wanted to buy another bottle.