Change the hand rail to something slimmer. Add a floating ceiling either using plaster board or timber. Add a outdoor heater, either down lights or rail lights. Add a fan for cooling and air movement, privacy screen between you and your neighbors so either new fencing or (in big pots or a bed) a green screen. Golden palms and bamboo are great to use and don't need much maintenance.

Your plans seem expansive and maybe costly. Id spend just a bit more and get a proper professional plan done.

Hi - is there a particular type of grout I should use for exterior verandah tiles? There has been slight movement I suspect. thanks.

I would second using tongue and groove flooring instead of slatted verandah timbers. You can still seal them with decking oils to protect them, and opt for a good hardwood timber that will last. Then, I would focus on keeping the rain out of the verandah. So... over extend the eaves a lot. In the tropics eaves go out a lot more and keep the torrential rain off the house walls. If the eaves are already built, they can easily be extended by splinting a longer beam to what's there and encasing it. You could go for the half-wall style verandah railing too. It's common where I live. So you completely clad the bottom half of the verandah, below the rail with vj timber and then you leave the top open, you can add the timber trims and traditional features if you like. That would stop rain blowing in as much too, you could even go so far as to install plantain shutters our simple timber louvres that can be pulled across in a downpour.