i wouldn't do the betta. they generally don't do well with tankmates, especially small things they can harass to death/eat, and schooling fish, which can stress them out. they also don't generally do well in large tanks just because they're used to smaller things. and then the flow that would come from a canister filter would be too high for them, it would probably tear up their fins. if you want a betta, i'd get a separate 5.5 or 10 gallon tank for one.
i don't think you should have a T8 and a T5HO bulb in the same fixture? i think it can ultimately fry the wiring, if you have two different types. you'd have good medium lighting with just the T5HO, according to this: https://www.plantedtank.net/forums/li...t5-t12-pc.html
that sword will get HUUGE. like... sometimes upwards of two feet. usually at least one foot. it might end up overcrowding your tank, but if you want to dedicate a lot of space for it then go for it because they're beautiful.
will your tank be covered? i've heard a lot of CPD's jumping. figure it will be, considering your lighting selection, but just making sure.
umm. and then if you're picky about little things, if you get nerites, they'll lay hideous blobs of white eggs that are near impossible to get off all around your tank. but if you don't mind that then it's okay.
also i'd consider getting more otos and supplementing their diet with repashy foods or algae wafers, they're a lot happier in larger groups. but 3-4 should be okay too.
as for scaping a tall aquarium, i'd make sure to use some driftwood. it's just a really good opportunity to use a tall branch, and turns out looking great.