I've heard that you can mix flourite up to about 50% with regular gravel before you really start to lose the benefits. I think folks mostly do this to economize on the big tanks. I used a sand/laterite blend and after a few weeks the plants are doing well. The next tank is going to be 100% flourite, so I can't compare yet, but the flourite folk all seem very enthusiastic about it.
I used about a pound a gallon to get maybe 1.5 to 3+ depth in a 30g.
I kicked up a huge cloud of sediment when I did the massive post-fishless waterchange. Sediment settled on my heater, creating a hotspot and causing it to shatter -- so be careful when its cloudy. Filtered out in a few days, cleaning the filter twice a day.
I wouldn't think you'd have any trouble with the remodel with a cycled filter and the plants especially with the low bioload. I introduced plants and fish at the same time following fishless, fully stocked on fish after about a week. No problems.
If you're looking for a weed to outcompete the algae while you get established ambulia (limnophilla sessiflora) must be seen to be believed. I think I'm going to throw out half of it tomorrow -- it doubles in volume every few days, looks a lot like cabomba. You can almost see it growing, at least an inch or two a day. I started with maybe a half dozen 6 inch stems. I now have over a dozen plants, several with multiple stems all at or near the surface two weeks later. I cut it back on Thursday or Friday and will again tomorrow.
Good luck with the transition, you'll love it.