Regarding the 'slippery' issue, make sure the tiles have a high 'slip rating' and are made for outdoor use. It looks like you're locked in to a thinner tile as your drain has been set for that. Modern porcelain tiles are very strong. If the area is for vehicular access as well make sure the tile is guaranteed for that purpose. There won't be a weed issue as the tiles will be glued onto the concrete. The tile which most closely matches or blends in with the detail tiles on your verandah will probably look best. If you're leaving the verandah as is then it's possible that a narrow terracotta tile which matches the verandah terracotta will look good as an insert inside the main border. Get hold of some tiles and see what they'd look like in that combination.

Outdoor Or textured tiles certainly can be used inside provided it’s the right setting or area, for instance a laundry or smaller bathroom and en-suite... you just need the right cleaning equipment such as a sponge mop rather than a soft mop head and a good quality stone and tile cleaner. AquaKleen is a great brand. You’ll achieve a much more natural stone feel underfoot much like a natural stone ... with little to no slip or shine. Many people do use them and suppliers can shy away from recommending however they are completely fine to use indoors with the right equipment to clean.

metal posts can be bolted to the concrete floor with a metal bracket called a "stirrup" there's a brand called Uni-pier with multiple sizes available at the major hardware stores and then attach sections of plastic lattice (friendlier for attaching plants) ...make sure the posts are installed at standard distances to suit the size of the panels..eg four panels 1200 wide x 2400 tall installed between 5 posts would allow for a wide doorway at one end or two panels could be installed horizontally between three posts with gaps at the top and bottom with a line of big oblong shaped pots for climbing plants and wall hung pots could be attached to the lattice

my suggestion would be a solid brick wall with full width lowlight double glazed sound proof sliding windows (about 750 of the floor and only about 600 mm tall so that you can look at your gorgeous palms from a seated position without seeing above the fence, also add matching sliding glass doors to completely enclose the space and paint the new wall a dark colour so the focus is on the view....and, if you don't already have some roof ventilation a ceiling fan and roof vent will make the space more comfortable when you need to keep it all closed up for privacy and the side fence needs to be tightened up to cover the gaps and also paint the whole fence in the darkest colour to highlight the palms...sound is like air and water and can squeeze through the smallest gaps so all this effort and expense will be a great investment in your peace and privacy