Do have any pics of the female? My "pet store" betta male was too old to breed, but my female was bought as a fry (petco sells baby bettas). This time I plan on buying only the baby bettas, so I can raise them (thus they won't be too old). I would recommend doing that instead of buying full grown males/females. Or if you can buying from a breeder is always a good choice. Good luck!
That ornament looks like it might be rather rough. They dash and thrash around a lot while they are courting and that think looks like they might get hurt on it. That should be big enough I think, barely (Thai breeders often use the bottom of 5 gallon buckets), will just have to move them sooner into a larger tank to grow out. And if the bettas are older, they will just fight, and not spawn.